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7.1.3 - 2020-11-24

  • Fixed handling of buffer boundaries in format_to_n (fmtlib#1996, fmtlib#2029).
  • Fixed linkage errors when linking with a shared library (fmtlib#2011).
  • Reintroduced ostream support to range formatters (fmtlib#2014).
  • Worked around an issue with mixing std versions in gcc (fmtlib#2017).

7.1.2 - 2020-11-04

  • Fixed floating point formatting with large precision (fmtlib#1976).

7.1.1 - 2020-11-01

  • Fixed ABI compatibility with 7.0.x (fmtlib#1961).
  • Added the FMT_ARM_ABI_COMPATIBILITY macro to work around ABI incompatibility between GCC and Clang on ARM (fmtlib#1919).
  • Worked around a SFINAE bug in GCC 8 (fmtlib#1957).
  • Fixed linkage errors when building with GCC's LTO (fmtlib#1955).
  • Fixed a compilation error when building without __builtin_clz or equivalent (fmtlib#1968). Thanks @tohammer.
  • Fixed a sign conversion warning (fmtlib#1964). Thanks @OptoCloud.

7.1.0 - 2020-10-25

  • Switched from Grisu3 to Dragonbox for the default floating-point formatting which gives the shortest decimal representation with round-trip guarantee and correct rounding (fmtlib#1882, fmtlib#1887, fmtlib#1894). This makes {fmt} up to 20-30x faster than common implementations of std::ostringstream and sprintf on dtoa-benchmark and faster than double-conversion and Ryū:

    It is possible to get even better performance at the cost of larger binary size by compiling with the FMT_USE_FULL_CACHE_DRAGONBOX macro set to 1.

    Thanks @jk-jeon.

  • Added an experimental unsynchronized file output API which, together with format string compilation, can give 5-9 times speed up compared to fprintf on common platforms (godbolt):

    #include <fmt/os.h>

int main() {
  auto f = fmt::output_file("guide");
  f.print("The answer is {}.", 42);
}

  • Added a formatter for std::chrono::time_point<system_clock> (fmtlib#1819, fmtlib#1837). For example (godbolt):

    #include <fmt/chrono.h>

int main() {
  auto now = std::chrono::system_clock::now();
  fmt::print("The time is {:%H:%M:%S}.\n", now);
}

    Thanks @adamburgess.

  • Added support for ranges with non-const begin/end to fmt::join (fmtlib#1784, fmtlib#1786). For example (godbolt):

    #include <fmt/ranges.h>
#include <range/v3/view/filter.hpp>

int main() {
  using std::literals::string_literals::operator""s;
  auto strs = std::array{"a"s, "bb"s, "ccc"s};
  auto range = strs | ranges::views::filter(
    [] (const std::string &x) { return x.size() != 2; }
  );
  fmt::print("{}\n", fmt::join(range, ""));
}

    prints "accc".

    Thanks @tonyelewis.

  • Added a memory_buffer::append overload that takes a range (fmtlib#1806). Thanks @BRevzin.

  • Improved handling of single code units in FMT_COMPILE. For example:

    #include <fmt/compile.h>

char* f(char* buf) {
  return fmt::format_to(buf, FMT_COMPILE("x{}"), 42);
}

    compiles to just (godbolt):

    _Z1fPc:
  movb $120, (%rdi)
  xorl %edx, %edx
  cmpl $42, _ZN3fmt2v76detail10basic_dataIvE23zero_or_powers_of_10_32E+8(%rip)
  movl $3, %eax
  seta %dl
  subl %edx, %eax
  movzwl _ZN3fmt2v76detail10basic_dataIvE6digitsE+84(%rip), %edx
  cltq
  addq %rdi, %rax
  movw %dx, -2(%rax)
  ret

    Here a single mov instruction writes 'x' ($120) to the output buffer.

  • Added dynamic width support to format string compilation (fmtlib#1809).

  • Improved error reporting for unformattable types: now you'll get the type name directly in the error message instead of the note:

    #include <fmt/core.h>

struct how_about_no {};

int main() {
  fmt::print("{}", how_about_no());
}

    Error (godbolt):

    fmt/core.h:1438:3: error: static_assert failed due to requirement 'fmt::v7::formattable<how_about_no>()' "Cannot format an argument. To make type T formattable provide a formatter<T> specialization: https://fmt.dev/latest/api.html#udt" ...

  • Added the make_args_checked function template that allows you to write formatting functions with compile-time format string checks and avoid binary code bloat (godbolt):

    void vlog(const char* file, int line, fmt::string_view format,
          fmt::format_args args) {
  fmt::print("{}: {}: ", file, line);
  fmt::vprint(format, args);
}

template <typename S, typename... Args>
void log(const char* file, int line, const S& format, Args&&... args) {
  vlog(file, line, format,
      fmt::make_args_checked<Args...>(format, args...));
}

#define MY_LOG(format, ...) \
  log(__FILE__, __LINE__, FMT_STRING(format), __VA_ARGS__)

MY_LOG("invalid squishiness: {}", 42);

  • Replaced snprintf fallback with a faster internal IEEE 754 float and double formatter for arbitrary precision. For example (godbolt):

    #include <fmt/core.h>

int main() {
  fmt::print("{:.500}\n", 4.9406564584124654E-324);
}

    prints

    4.9406564584124654417656879286822137236505980261432476442558568250067550727020875186529983636163599237979656469544571773092665671035593979639877479601078187812630071319031140452784581716784898210368871863605699873072305000638740915356498438731247339727316961514003171538539807412623856559117102665855668676818703956031062493194527159149245532930545654440112748012970999954193198940908041656332452475714786901472678015935523861155013480352649347201937902681071074917033322268447533357208324319360923829e-324.

  • Made format_to_n and formatted_size part of the core API (godbolt):

    #include <fmt/core.h>

int main() {
  char buffer[10];
  auto result = fmt::format_to_n(buffer, sizeof(buffer), "{}", 42);
}

  • Added fmt::format_to_n overload with format string compilation (fmtlib#1764, fmtlib#1767, fmtlib#1869). For example (godbolt):

    #include <fmt/compile.h>

int main() {
  char buffer[8];
  fmt::format_to_n(buffer, sizeof(buffer), FMT_COMPILE("{}"), 42);
}

    Thanks @Kurkin and @alexezeder.

  • Added fmt::format_to overload that take text_style (fmtlib#1593, fmtlib#1842, fmtlib#1843). For example (godbolt):

    #include <fmt/color.h>

int main() {
  std::string out;
  fmt::format_to(std::back_inserter(out),
                 fmt::emphasis::bold | fg(fmt::color::red),
                 "The answer is {}.", 42);
}

    Thanks @Naios.

  • Made the '#' specifier emit trailing zeros in addition to the decimal point (fmtlib#1797). For example (godbolt):

    #include <fmt/core.h>

int main() {
  fmt::print("{:#.2g}", 0.5);
}

    prints 0.50.

  • Changed the default floating point format to not include .0 for consistency with std::format and std::to_chars (fmtlib#1893, fmtlib#1943). It is possible to get the decimal point and trailing zero with the # specifier.

  • Fixed an issue with floating-point formatting that could result in addition of a non-significant trailing zero in rare cases e.g. 1.00e-34 instead of 1.0e-34 (fmtlib#1873, fmtlib#1917).

  • Made fmt::to_string fallback on ostream insertion operator if the formatter specialization is not provided (fmtlib#1815, fmtlib#1829). Thanks @alexezeder.

  • Added support for the append mode to the experimental file API and improved fcntl.h detection. (fmtlib#1847, fmtlib#1848). Thanks @t-wiser.

  • Fixed handling of types that have both an implicit conversion operator and an overloaded ostream insertion operator (fmtlib#1766).

  • Fixed a slicing issue in an internal iterator type (fmtlib#1822). Thanks @BRevzin.

  • Fixed an issue in locale-specific integer formatting (fmtlib#1927).

  • Fixed handling of exotic code unit types (fmtlib#1870, fmtlib#1932).

  • Improved FMT_ALWAYS_INLINE (fmtlib#1878). Thanks @jk-jeon.

  • Removed dependency on windows.h (fmtlib#1900). Thanks @bernd5.

  • Optimized counting of decimal digits on MSVC (fmtlib#1890). Thanks @mwinterb.

  • Improved documentation (fmtlib#1772, fmtlib#1775, fmtlib#1792, fmtlib#1838, fmtlib#1888, fmtlib#1918, fmtlib#1939). Thanks @leolchat, @pepsiman, @Klaim, @ravijanjam, @francesco-st and @udnaan.

  • Added the FMT_REDUCE_INT_INSTANTIATIONS CMake option that reduces the binary code size at the cost of some integer formatting performance. This can be useful for extremely memory-constrained embedded systems (fmtlib#1778, fmtlib#1781). Thanks @kammce.

  • Added the FMT_USE_INLINE_NAMESPACES macro to control usage of inline namespaces (fmtlib#1945). Thanks @darklukee.

  • Improved build configuration (fmtlib#1760, fmtlib#1770, fmtlib#1779, fmtlib#1783, fmtlib#1823). Thanks @dvetutnev, @xvitaly, @tambry, @medithe and @martinwuehrer.

  • Fixed various warnings and compilation issues (fmtlib#1790, fmtlib#1802, fmtlib#1808, fmtlib#1810, fmtlib#1811, fmtlib#1812, fmtlib#1814, fmtlib#1816, fmtlib#1817, fmtlib#1818, fmtlib#1825, fmtlib#1836, fmtlib#1855, fmtlib#1856, fmtlib#1860, fmtlib#1877, fmtlib#1879, fmtlib#1880, fmtlib#1896, fmtlib#1897, fmtlib#1898, fmtlib#1904, fmtlib#1908, fmtlib#1911, fmtlib#1912, fmtlib#1928, fmtlib#1929, fmtlib#1935, fmtlib#1937, fmtlib#1942, fmtlib#1949). Thanks @TheQwertiest, @medithe, @martinwuehrer, @n16h7hunt3r, @Othereum, @gsjaardema, @AlexanderLanin, @gcerretani, @chronoxor, @noizefloor, @akohlmey, @jk-jeon, @rimathia, @rglarix, @moiwi, @heckad, @MarcDirven. @BartSiwek and @darklukee.

7.0.3 - 2020-08-06

  • Worked around broken numeric_limits for 128-bit integers (fmtlib#1787).
  • Added error reporting on missing named arguments (fmtlib#1796).
  • Stopped using 128-bit integers with clang-cl (fmtlib#1800). Thanks @Kingcom.
  • Fixed issues in locale-specific integer formatting (fmtlib#1782, fmtlib#1801).

7.0.2 - 2020-07-29

  • Worked around broken numeric_limits for 128-bit integers (fmtlib#1725).
  • Fixed compatibility with CMake 3.4 (fmtlib#1779).
  • Fixed handling of digit separators in locale-specific formatting (fmtlib#1782).

7.0.1 - 2020-07-07

  • Updated the inline version namespace name.
  • Worked around a gcc bug in mangling of alias templates (fmtlib#1753).
  • Fixed a linkage error on Windows (fmtlib#1757). Thanks @Kurkin.
  • Fixed minor issues with the documentation.

7.0.0 - 2020-07-05

  • Reduced the library size. For example, on macOS a stripped test binary statically linked with {fmt} shrank from ~368k to less than 100k.

  • Added a simpler and more efficient format string compilation API:

    #include <fmt/compile.h>

// Converts 42 into std::string using the most efficient method and no
// runtime format string processing.
std::string s = fmt::format(FMT_COMPILE("{}"), 42);

    The old fmt::compile API is now deprecated.

  • Optimized integer formatting: format_to with format string compilation and a stack-allocated buffer is now faster than to_chars on both libc++ and libstdc++.

  • Optimized handling of small format strings. For example,

    fmt::format("Result: {}: ({},{},{},{})", str1, str2, str3, str4, str5)

    is now ~40% faster (fmtlib#1685).

  • Applied extern templates to improve compile times when using the core API and fmt/format.h (fmtlib#1452). For example, on macOS with clang the compile time of a test translation unit dropped from 2.3s to 0.3s with -O2 and from 0.6s to 0.3s with the default settings (-O0).

    Before (-O2):

    % time c++ -c test.cc -I include -std=c++17 -O2
c++ -c test.cc -I include -std=c++17 -O2  2.22s user 0.08s system 99% cpu 2.311 total

    After (-O2):

    % time c++ -c test.cc -I include -std=c++17 -O2
c++ -c test.cc -I include -std=c++17 -O2  0.26s user 0.04s system 98% cpu 0.303 total

    Before (default):

    % time c++ -c test.cc -I include -std=c++17
c++ -c test.cc -I include -std=c++17  0.53s user 0.06s system 98% cpu 0.601 total

    After (default):

    % time c++ -c test.cc -I include -std=c++17
c++ -c test.cc -I include -std=c++17  0.24s user 0.06s system 98% cpu 0.301 total

    It is still recommended to use fmt/core.h instead of fmt/format.h but the compile time difference is now smaller. Thanks @alex3d for the suggestion.

  • Named arguments are now stored on stack (no dynamic memory allocations) and the compiled code is more compact and efficient. For example

    #include <fmt/core.h>

int main() {
  fmt::print("The answer is {answer}\n", fmt::arg("answer", 42));
}

    compiles to just (godbolt)

    .LC0:
        .string "answer"
.LC1:
        .string "The answer is {answer}\n"
main:
        sub     rsp, 56
        mov     edi, OFFSET FLAT:.LC1
        mov     esi, 23
        movabs  rdx, 4611686018427387905
        lea     rax, [rsp+32]
        lea     rcx, [rsp+16]
        mov     QWORD PTR [rsp+8], 1
        mov     QWORD PTR [rsp], rax
        mov     DWORD PTR [rsp+16], 42
        mov     QWORD PTR [rsp+32], OFFSET FLAT:.LC0
        mov     DWORD PTR [rsp+40], 0
        call    fmt::v6::vprint(fmt::v6::basic_string_view<char>,
                                fmt::v6::format_args)
        xor     eax, eax
        add     rsp, 56
        ret

    .L.str.1:
            .asciz  "answer"

  • Implemented compile-time checks for dynamic width and precision (fmtlib#1614):

    #include <fmt/format.h>

int main() {
  fmt::print(FMT_STRING("{0:{1}}"), 42);
}

    now gives a compilation error because argument 1 doesn't exist:

    In file included from test.cc:1:
include/fmt/format.h:2726:27: error: constexpr variable 'invalid_format' must be
initialized by a constant expression
  FMT_CONSTEXPR_DECL bool invalid_format =
                          ^
...
include/fmt/core.h:569:26: note: in call to
'&checker(s, {}).context_->on_error(&"argument not found"[0])'
    if (id >= num_args_) on_error("argument not found");
                        ^

  • Added sentinel support to fmt::join (fmtlib#1689)

    struct zstring_sentinel {};
bool operator==(const char* p, zstring_sentinel) { return *p == '\0'; }
bool operator!=(const char* p, zstring_sentinel) { return *p != '\0'; }

struct zstring {
  const char* p;
  const char* begin() const { return p; }
  zstring_sentinel end() const { return {}; }
};

auto s = fmt::format("{}", fmt::join(zstring{"hello"}, "_"));
// s == "h_e_l_l_o"

    Thanks @BRevzin.

  • Added support for named arguments, clear and reserve to dynamic_format_arg_store (fmtlib#1655, fmtlib#1663, fmtlib#1674, fmtlib#1677). Thanks @vsolontsov-ll.

  • Added support for the 'c' format specifier to integral types for compatibility with std::format (fmtlib#1652).

  • Replaced the 'n' format specifier with 'L' for compatibility with std::format (fmtlib#1624). The 'n' specifier can be enabled via the FMT_DEPRECATED_N_SPECIFIER macro.

  • The '=' format specifier is now disabled by default for compatibility with std::format. It can be enabled via the FMT_DEPRECATED_NUMERIC_ALIGN macro.

  • Removed the following deprecated APIs:

    • FMT_STRING_ALIAS and fmt macros - replaced by FMT_STRING
    • fmt::basic_string_view::char_type - replaced by fmt::basic_string_view::value_type
    • convert_to_int
    • format_arg_store::types
    • *parse_context - replaced by *format_parse_context
    • FMT_DEPRECATED_INCLUDE_OS
    • FMT_DEPRECATED_PERCENT - incompatible with std::format
    • *writer - replaced by compiled format API

  • Renamed the internal namespace to detail (fmtlib#1538). The former is still provided as an alias if the FMT_USE_INTERNAL macro is defined.

  • Improved compatibility between fmt::printf with the standard specs (fmtlib#1595, fmtlib#1682, fmtlib#1683, fmtlib#1687, fmtlib#1699). Thanks @rimathia.

  • Fixed handling of operator<< overloads that use copyfmt (fmtlib#1666).

  • Added the FMT_OS CMake option to control inclusion of OS-specific APIs in the fmt target. This can be useful for embedded platforms (fmtlib#1654, fmtlib#1656). Thanks @kwesolowski.

  • Replaced FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION with the FMT_FUZZ macro to prevent interfering with fuzzing of projects using {fmt} (fmtlib#1650). Thanks @asraa.

  • Fixed compatibility with emscripten (fmtlib#1636, fmtlib#1637). Thanks @ArthurSonzogni.

  • Improved documentation (fmtlib#704, fmtlib#1643, fmtlib#1660, fmtlib#1681, fmtlib#1691, fmtlib#1706, fmtlib#1714, fmtlib#1721, fmtlib#1739, fmtlib#1740, fmtlib#1741, fmtlib#1751). Thanks @senior7515, @lsr0, @puetzk, @fpelliccioni, Alexey Kuzmenko, @jelly, @claremacrae, @jiapengwen, @gsjaardema and @alexey-milovidov.

  • Implemented various build configuration fixes and improvements (fmtlib#1603, fmtlib#1657, fmtlib#1702, fmtlib#1728). Thanks @scramsby, @jtojnar, @orivej and @flagarde.

  • Fixed various warnings and compilation issues (fmtlib#1616, fmtlib#1620, fmtlib#1622, fmtlib#1625, fmtlib#1627, fmtlib#1628, fmtlib#1629, fmtlib#1631, fmtlib#1633, fmtlib#1649, fmtlib#1658, fmtlib#1661, fmtlib#1667, fmtlib#1668, fmtlib#1669, fmtlib#1692, fmtlib#1696, fmtlib#1697, fmtlib#1707, fmtlib#1712, fmtlib#1716, fmtlib#1722, fmtlib#1724, fmtlib#1729, fmtlib#1738, fmtlib#1742, fmtlib#1743, fmtlib#1744, fmtlib#1747, fmtlib#1750). Thanks @gsjaardema, @gabime, @johnor, @Kurkin, @invexed, @peterbell10, @daixtrose, @petrutlucian94, @Neargye, @ambitslix, @gabime, @tohammer and @0x8000-0000.

6.2.1 - 2020-05-09

  • Fixed ostream support in sprintf (fmtlib#1631).
  • Fixed type detection when using implicit conversion to string_view and ostream operator<< inconsistently (fmtlib#1662).

6.2.0 - 2020-04-05

  • Improved error reporting when trying to format an object of a non-formattable type:

    fmt::format("{}", S());

    now gives:

    include/fmt/core.h:1015:5: error: static_assert failed due to requirement
'formattable' "Cannot format argument. To make type T formattable provide a
formatter<T> specialization:
https://fmt.dev/latest/api.html#formatting-user-defined-types"
    static_assert(
    ^
...
note: in instantiation of function template specialization
'fmt::v6::format<char [3], S, char>' requested here
  fmt::format("{}", S());
       ^

    if S is not formattable.

  • Reduced the library size by ~10%.

  • Always print decimal point if # is specified (fmtlib#1476, fmtlib#1498):

    fmt::print("{:#.0f}", 42.0);

    now prints 42.

  • Implemented the 'L' specifier for locale-specific numeric formatting to improve compatibility with std::format. The 'n' specifier is now deprecated and will be removed in the next major release.

  • Moved OS-specific APIs such as windows_error from fmt/format.h to fmt/os.h. You can define FMT_DEPRECATED_INCLUDE_OS to automatically include fmt/os.h from fmt/format.h for compatibility but this will be disabled in the next major release.

  • Added precision overflow detection in floating-point formatting.

  • Implemented detection of invalid use of fmt::arg.

  • Used type_identity to block unnecessary template argument deduction. Thanks Tim Song.

  • Improved UTF-8 handling (fmtlib#1109):

    fmt::print("┌{0:─^{2}}┐\n"
           "│{1: ^{2}}│\n"
           "└{0:─^{2}}┘\n", "", "Прывітанне, свет!", 21);

    now prints:

    ┌─────────────────────┐
│  Прывітанне, свет!  │
└─────────────────────┘

    on systems that support Unicode.

  • Added experimental dynamic argument storage (fmtlib#1170, fmtlib#1584):

    fmt::dynamic_format_arg_store<fmt::format_context> store;
store.push_back("answer");
store.push_back(42);
fmt::vprint("The {} is {}.\n", store);

    prints:

    The answer is 42.

    Thanks @vsolontsov-ll.

  • Made fmt::join accept initializer_list (fmtlib#1591). Thanks @Rapotkinnik.

  • Fixed handling of empty tuples (fmtlib#1588).

  • Fixed handling of output iterators in format_to_n (fmtlib#1506).

  • Fixed formatting of std::chrono::duration types to wide output (fmtlib#1533). Thanks @zeffy.

  • Added const begin and end overload to buffers (fmtlib#1553). Thanks @dominicpoeschko.

  • Added the ability to disable floating-point formatting via FMT_USE_FLOAT, FMT_USE_DOUBLE and FMT_USE_LONG_DOUBLE macros for extremely memory-constrained embedded system (fmtlib#1590). Thanks @albaguirre.

  • Made FMT_STRING work with constexpr string_view (fmtlib#1589). Thanks @scramsby.

  • Implemented a minor optimization in the format string parser (fmtlib#1560). Thanks @IkarusDeveloper.

  • Improved attribute detection (fmtlib#1469, fmtlib#1475, fmtlib#1576). Thanks @federico-busato, @chronoxor and @refnum.

  • Improved documentation (fmtlib#1481, fmtlib#1523). Thanks @JackBoosY and @imba-tjd.

  • Fixed symbol visibility on Linux when compiling with -fvisibility=hidden (fmtlib#1535). Thanks @milianw.

  • Implemented various build configuration fixes and improvements (fmtlib#1264, fmtlib#1460, fmtlib#1534, fmtlib#1536, fmtlib#1545, fmtlib#1546, fmtlib#1566, fmtlib#1582, fmtlib#1597, fmtlib#1598). Thanks @ambitslix, @jwillikers and @stac47.

  • Fixed various warnings and compilation issues (fmtlib#1433, fmtlib#1461, fmtlib#1470, fmtlib#1480, fmtlib#1485, fmtlib#1492, fmtlib#1493, fmtlib#1504, fmtlib#1505, fmtlib#1512, fmtlib#1515, fmtlib#1516, fmtlib#1518, fmtlib#1519, fmtlib#1520, fmtlib#1521, fmtlib#1522, fmtlib#1524, fmtlib#1530, fmtlib#1531, fmtlib#1532, fmtlib#1539, fmtlib#1547, fmtlib#1548, fmtlib#1554, fmtlib#1567, fmtlib#1568, fmtlib#1569, fmtlib#1571, fmtlib#1573, fmtlib#1575, fmtlib#1581, fmtlib#1583, fmtlib#1586, fmtlib#1587, fmtlib#1594, fmtlib#1596, fmtlib#1604, fmtlib#1606, fmtlib#1607, fmtlib#1609). Thanks @marti4d, @iPherian, @parkertomatoes, @gsjaardema, @chronoxor, @DanielaE, @torsten48, @tohammer, @lefticus, @ryusakki, @adnsv, @fghzxm, @refnum, @pramodk, @Spirrwell and @scramsby.

6.1.2 - 2019-12-11

  • Fixed ABI compatibility with libfmt.so.6.0.0 (fmtlib#1471).
  • Fixed handling types convertible to std::string_view (fmtlib#1451). Thanks @denizevrenci.
  • Made CUDA test an opt-in enabled via the FMT_CUDA_TEST CMake option.
  • Fixed sign conversion warnings (fmtlib#1440). Thanks @0x8000-0000.

6.1.1 - 2019-12-04

  • Fixed shared library build on Windows (fmtlib#1443, fmtlib#1445, fmtlib#1446, fmtlib#1450). Thanks @egorpugin and @bbolli.
  • Added a missing decimal point in exponent notation with trailing zeros.
  • Removed deprecated format_arg_store::TYPES.

6.1.0 - 2019-12-01

  • {fmt} now formats IEEE 754 float and double using the shortest decimal representation with correct rounding by default:

    #include <cmath>
#include <fmt/core.h>

int main() {
  fmt::print("{}", M_PI);
}

    prints 3.141592653589793.

  • Made the fast binary to decimal floating-point formatter the default, simplified it and improved performance. {fmt} is now 15 times faster than libc++'s std::ostringstream, 11 times faster than printf and 10% faster than double-conversion on dtoa-benchmark:

    Function Time (ns) Speedup
    ostringstream 1,346.30 1.00x
    ostrstream 1,195.74 1.13x
    sprintf 995.08 1.35x
    doubleconv 99.10 13.59x
    fmt 88.34 15.24x

  • {fmt} no longer converts float arguments to double. In particular this improves the default (shortest) representation of floats and makes fmt::format consistent with std::format specs (fmtlib#1336, fmtlib#1353, fmtlib#1360, fmtlib#1361):

    fmt::print("{}", 0.1f);

    prints 0.1 instead of 0.10000000149011612.

    Thanks @orivej.

  • Made floating-point formatting output consistent with printf/iostreams (fmtlib#1376, fmtlib#1417).

  • Added support for 128-bit integers (fmtlib#1287):

    fmt::print("{}", std::numeric_limits<__int128_t>::max());

    prints 170141183460469231731687303715884105727.

    Thanks @denizevrenci.

  • The overload of print that takes text_style is now atomic, i.e. the output from different threads doesn't interleave (fmtlib#1351). Thanks @tankiJong.

  • Made compile time in the header-only mode ~20% faster by reducing the number of template instantiations. wchar_t overload of vprint was moved from fmt/core.h to fmt/format.h.

  • Added an overload of fmt::join that works with tuples (fmtlib#1322, fmtlib#1330):

    #include <tuple>
#include <fmt/ranges.h>

int main() {
  std::tuple<char, int, float> t{'a', 1, 2.0f};
  fmt::print("{}", t);
}

    prints ('a', 1, 2.0).

    Thanks @jeremyong.

  • Changed formatting of octal zero with prefix from "00" to "0":

    fmt::print("{:#o}", 0);

    prints 0.

  • The locale is now passed to ostream insertion (<<) operators (fmtlib#1406):

    #include <fmt/locale.h>
#include <fmt/ostream.h>

struct S {
  double value;
};

std::ostream& operator<<(std::ostream& os, S s) {
  return os << s.value;
}

int main() {
  auto s = fmt::format(std::locale("fr_FR.UTF-8"), "{}", S{0.42});
  // s == "0,42"
}

    Thanks @dlaugt.

  • Locale-specific number formatting now uses grouping (fmtlib#1393, fmtlib#1394). Thanks @skrdaniel.

  • Fixed handling of types with deleted implicit rvalue conversion to const char** (fmtlib#1421):

    struct mystring {
  operator const char*() const&;
  operator const char*() &;
  operator const char*() const&& = delete;
  operator const char*() && = delete;
};
mystring str;
fmt::print("{}", str); // now compiles

  • Enums are now mapped to correct underlying types instead of int (fmtlib#1286). Thanks @agmt.

  • Enum classes are no longer implicitly converted to int (fmtlib#1424).

  • Added basic_format_parse_context for consistency with C++20 std::format and deprecated basic_parse_context.

  • Fixed handling of UTF-8 in precision (fmtlib#1389, fmtlib#1390). Thanks @tajtiattila.

  • {fmt} can now be installed on Linux, macOS and Windows with Conda using its conda-forge package (fmtlib#1410):

    conda install -c conda-forge fmt

    Thanks @tdegeus.

  • Added a CUDA test (fmtlib#1285, fmtlib#1317). Thanks @luncliff and @risa2000.

  • Improved documentation (fmtlib#1276, fmtlib#1291, fmtlib#1296, fmtlib#1315, fmtlib#1332, fmtlib#1337, fmtlib#1395 fmtlib#1418). Thanks @waywardmonkeys, @pauldreik and @jackoalan.

  • Various code improvements (fmtlib#1358, fmtlib#1407). Thanks @orivej and @dpacbach.

  • Fixed compile-time format string checks for user-defined types (fmtlib#1292).

  • Worked around a false positive in unsigned-integer-overflow sanitizer (fmtlib#1377).

  • Fixed various warnings and compilation issues (fmtlib#1273, fmtlib#1278, fmtlib#1280, fmtlib#1281, fmtlib#1288, fmtlib#1290, fmtlib#1301, fmtlib#1305, fmtlib#1306, fmtlib#1309, fmtlib#1312, fmtlib#1313, fmtlib#1316, fmtlib#1319, fmtlib#1320, fmtlib#1326, fmtlib#1328, fmtlib#1344, fmtlib#1345, fmtlib#1347, fmtlib#1349, fmtlib#1354, fmtlib#1362, fmtlib#1366, fmtlib#1364, fmtlib#1370, fmtlib#1371, fmtlib#1385, fmtlib#1388, fmtlib#1397, fmtlib#1414, fmtlib#1416, fmtlib#1422 fmtlib#1427, fmtlib#1431, fmtlib#1433). Thanks @hhb, @gsjaardema, @gabime, @neheb, @vedranmiletic, @dkavolis, @mwinterb, @orivej, @denizevrenci, @leonklingele, @chronoxor, @kent-tri, @0x8000-0000 and @marti4d.

6.0.0 - 2019-08-26

  • Switched to the MIT license with an optional exception that allows distributing binary code without attribution.

  • Floating-point formatting is now locale-independent by default:

    #include <locale>
#include <fmt/core.h>

int main() {
  std::locale::global(std::locale("ru_RU.UTF-8"));
  fmt::print("value = {}", 4.2);
}

    prints "value = 4.2" regardless of the locale.

    For locale-specific formatting use the n specifier:

    std::locale::global(std::locale("ru_RU.UTF-8"));
fmt::print("value = {:n}", 4.2);

    prints "value = 4,2".

  • Added an experimental Grisu floating-point formatting algorithm implementation (disabled by default). To enable it compile with the FMT_USE_GRISU macro defined to 1:

    #define FMT_USE_GRISU 1
#include <fmt/format.h>

auto s = fmt::format("{}", 4.2); // formats 4.2 using Grisu

    With Grisu enabled, {fmt} is 13x faster than std::ostringstream (libc++) and 10x faster than sprintf on dtoa-benchmark (full results):

  • Separated formatting and parsing contexts for consistency with C++20 std::format, removing the undocumented basic_format_context::parse_context() function.

  • Added oss-fuzz support (fmtlib#1199). Thanks @pauldreik.

  • formatter specializations now always take precedence over operator<< (fmtlib#952):

    #include <iostream>
#include <fmt/ostream.h>

struct S {};

std::ostream& operator<<(std::ostream& os, S) {
  return os << 1;
}

template <>
struct fmt::formatter<S> : fmt::formatter<int> {
  auto format(S, format_context& ctx) {
    return formatter<int>::format(2, ctx);
  }
};

int main() {
  std::cout << S() << "\n"; // prints 1 using operator<<
  fmt::print("{}\n", S());  // prints 2 using formatter
}

  • Introduced the experimental fmt::compile function that does format string compilation (fmtlib#618, fmtlib#1169, fmtlib#1171):

    #include <fmt/compile.h>

auto f = fmt::compile<int>("{}");
std::string s = fmt::format(f, 42); // can be called multiple times to
                                    // format different values
// s == "42"

    It moves the cost of parsing a format string outside of the format function which can be beneficial when identically formatting many objects of the same types. Thanks @stryku.

  • Added experimental % format specifier that formats floating-point values as percentages (fmtlib#1060, fmtlib#1069, fmtlib#1071):

    auto s = fmt::format("{:.1%}", 0.42); // s == "42.0%"

    Thanks @gawain-bolton.

  • Implemented precision for floating-point durations (fmtlib#1004, fmtlib#1012):

    auto s = fmt::format("{:.1}", std::chrono::duration<double>(1.234));
// s == 1.2s

    Thanks @DanielaE.

  • Implemented chrono format specifiers %Q and %q that give the value and the unit respectively (fmtlib#1019):

    auto value = fmt::format("{:%Q}", 42s); // value == "42"
auto unit  = fmt::format("{:%q}", 42s); // unit == "s"

    Thanks @DanielaE.

  • Fixed handling of dynamic width in chrono formatter:

    auto s = fmt::format("{0:{1}%H:%M:%S}", std::chrono::seconds(12345), 12);
//                        ^ width argument index                     ^ width
// s == "03:25:45    "

    Thanks Howard Hinnant.

  • Removed deprecated fmt/time.h. Use fmt/chrono.h instead.

  • Added fmt::format and fmt::vformat overloads that take text_style (fmtlib#993, fmtlib#994):

    #include <fmt/color.h>

std::string message = fmt::format(fmt::emphasis::bold | fg(fmt::color::red),
                                  "The answer is {}.", 42);

    Thanks @Naios.

  • Removed the deprecated color API (print_colored). Use the new API, namely print overloads that take text_style instead.

  • Made std::unique_ptr and std::shared_ptr formattable as pointers via fmt::ptr (fmtlib#1121):

    std::unique_ptr<int> p = ...;
fmt::print("{}", fmt::ptr(p)); // prints p as a pointer

    Thanks @sighingnow.

  • Made print and vprint report I/O errors (fmtlib#1098, fmtlib#1099). Thanks @BillyDonahue.

  • Marked deprecated APIs with the [[deprecated]] attribute and removed internal uses of deprecated APIs (fmtlib#1022). Thanks @eliaskosunen.

  • Modernized the codebase using more C++11 features and removing workarounds. Most importantly, buffer_context is now an alias template, so use buffer_context<T> instead of buffer_context<T>::type. These features require GCC 4.8 or later.

  • formatter specializations now always take precedence over implicit conversions to int and the undocumented convert_to_int trait is now deprecated.

  • Moved the undocumented basic_writer, writer, and wwriter types to the internal namespace.

  • Removed deprecated basic_format_context::begin(). Use out() instead.

  • Disallowed passing the result of join as an lvalue to prevent misuse.

  • Refactored the undocumented structs that represent parsed format specifiers to simplify the API and allow multibyte fill.

  • Moved SFINAE to template parameters to reduce symbol sizes.

  • Switched to fputws for writing wide strings so that it's no longer required to call _setmode on Windows (fmtlib#1229, fmtlib#1243). Thanks @jackoalan.

  • Improved literal-based API (fmtlib#1254). Thanks @sylveon.

  • Added support for exotic platforms without uintptr_t such as IBM i (AS/400) which has 128-bit pointers and only 64-bit integers (fmtlib#1059).

  • Added Sublime Text syntax highlighting config (fmtlib#1037). Thanks @Kronuz.

  • Added the FMT_ENFORCE_COMPILE_STRING macro to enforce the use of compile-time format strings (fmtlib#1231). Thanks @jackoalan.

  • Stopped setting CMAKE_BUILD_TYPE if {fmt} is a subproject (fmtlib#1081).

  • Various build improvements (fmtlib#1039, fmtlib#1078, fmtlib#1091, fmtlib#1103, fmtlib#1177). Thanks @luncliff, @jasonszang, @olafhering, @Lecetem and @pauldreik.

  • Improved documentation (fmtlib#1049, fmtlib#1051, fmtlib#1083, fmtlib#1113, fmtlib#1114, fmtlib#1146, fmtlib#1180, fmtlib#1250, fmtlib#1252, fmtlib#1265). Thanks @mikelui, @foonathan, @BillyDonahue, @jwakely, @kaisbe and @sdebionne.

  • Fixed ambiguous formatter specialization in fmt/ranges.h (fmtlib#1123).

  • Fixed formatting of a non-empty std::filesystem::path which is an infinitely deep range of its components (fmtlib#1268).

  • Fixed handling of general output iterators when formatting characters (fmtlib#1056, fmtlib#1058). Thanks @abolz.

  • Fixed handling of output iterators in formatter specialization for ranges (fmtlib#1064).

  • Fixed handling of exotic character types (fmtlib#1188).

  • Made chrono formatting work with exceptions disabled (fmtlib#1062).

  • Fixed DLL visibility issues (fmtlib#1134, fmtlib#1147). Thanks @denchat.

  • Disabled the use of UDL template extension on GCC 9 (fmtlib#1148).

  • Removed misplaced format compile-time checks from printf (fmtlib#1173).

  • Fixed issues in the experimental floating-point formatter (fmtlib#1072, fmtlib#1129, fmtlib#1153, fmtlib#1155, fmtlib#1210, fmtlib#1222). Thanks @alabuzhev.

  • Fixed bugs discovered by fuzzing or during fuzzing integration (fmtlib#1124, fmtlib#1127, fmtlib#1132, fmtlib#1135, fmtlib#1136, fmtlib#1141, fmtlib#1142, fmtlib#1178, fmtlib#1179, fmtlib#1194). Thanks @pauldreik.

  • Fixed building tests on FreeBSD and Hurd (fmtlib#1043). Thanks @jackyf.

  • Fixed various warnings and compilation issues (fmtlib#998, fmtlib#1006, fmtlib#1008, fmtlib#1011, fmtlib#1025, fmtlib#1027, fmtlib#1028, fmtlib#1029, fmtlib#1030, fmtlib#1031, fmtlib#1054, fmtlib#1063, fmtlib#1068, fmtlib#1074, fmtlib#1075, fmtlib#1079, fmtlib#1086, fmtlib#1088, fmtlib#1089, fmtlib#1094, fmtlib#1101, fmtlib#1102, fmtlib#1105, fmtlib#1107, fmtlib#1115, fmtlib#1117, fmtlib#1118, fmtlib#1120, fmtlib#1123, fmtlib#1139, fmtlib#1140, fmtlib#1143, fmtlib#1144, fmtlib#1150, fmtlib#1151, fmtlib#1152, fmtlib#1154, fmtlib#1156, fmtlib#1159, fmtlib#1175, fmtlib#1181, fmtlib#1186, fmtlib#1187, fmtlib#1191, fmtlib#1197, fmtlib#1200, fmtlib#1203, fmtlib#1205, fmtlib#1206, fmtlib#1213, fmtlib#1214, fmtlib#1217, fmtlib#1228, fmtlib#1230, fmtlib#1232, fmtlib#1235, fmtlib#1236, fmtlib#1240). Thanks @DanielaE, @mwinterb, @eliaskosunen, @morinmorin, @ricco19, @waywardmonkeys, @chronoxor, @remyabel, @pauldreik, @gsjaardema, @rcane, @mocabe, @denchat, @cjdb, @HazardyKnusperkeks, @vedranmiletic, @jackoalan, @DaanDeMeyer and @starkmapper.

5.3.0 - 2018-12-28

  • Introduced experimental chrono formatting support:

    #include <fmt/chrono.h>

int main() {
  using namespace std::literals::chrono_literals;
  fmt::print("Default format: {} {}\n", 42s, 100ms);
  fmt::print("strftime-like format: {:%H:%M:%S}\n", 3h + 15min + 30s);
}

    prints:

    Default format: 42s 100ms
strftime-like format: 03:15:30

  • Added experimental support for emphasis (bold, italic, underline, strikethrough), colored output to a file stream, and improved colored formatting API (fmtlib#961, fmtlib#967, fmtlib#973):

    #include <fmt/color.h>

int main() {
  fmt::print(fg(fmt::color::crimson) | fmt::emphasis::bold,
             "Hello, {}!\n", "world");
  fmt::print(fg(fmt::color::floral_white) | bg(fmt::color::slate_gray) |
             fmt::emphasis::underline, "Olá, {}!\n", "Mundo");
  fmt::print(fg(fmt::color::steel_blue) | fmt::emphasis::italic,
             "你好{}！\n", "世界");
}

    prints the following on modern terminals with RGB color support:

    Thanks @Rakete1111.

  • Added support for 4-bit terminal colors (fmtlib#968, fmtlib#974)

    #include <fmt/color.h>

int main() {
  print(fg(fmt::terminal_color::red), "stop\n");
}

    Note that these colors vary by terminal:

    Thanks @Rakete1111.

  • Parameterized formatting functions on the type of the format string (fmtlib#880, fmtlib#881, fmtlib#883, fmtlib#885, fmtlib#897, fmtlib#920). Any object of type S that has an overloaded to_string_view(const S&) returning fmt::string_view can be used as a format string:

    namespace my_ns {
inline string_view to_string_view(const my_string& s) {
  return {s.data(), s.length()};
}
}

std::string message = fmt::format(my_string("The answer is {}."), 42);

    Thanks @DanielaE.

  • Made std::string_view work as a format string (fmtlib#898):

    auto message = fmt::format(std::string_view("The answer is {}."), 42);

    Thanks @DanielaE.

  • Added wide string support to compile-time format string checks (fmtlib#924):

    print(fmt(L"{:f}"), 42); // compile-time error: invalid type specifier

    Thanks @XZiar.

  • Made colored print functions work with wide strings (fmtlib#867):

    #include <fmt/color.h>

int main() {
  print(fg(fmt::color::red), L"{}\n", 42);
}

    Thanks @DanielaE.

  • Introduced experimental Unicode support (fmtlib#628, fmtlib#891):

    using namespace fmt::literals;
auto s = fmt::format("{:*^5}"_u, "🤡"_u); // s == "**🤡**"_u

  • Improved locale support:

    #include <fmt/locale.h>

struct numpunct : std::numpunct<char> {
 protected:
  char do_thousands_sep() const override { return '~'; }
};

std::locale loc;
auto s = fmt::format(std::locale(loc, new numpunct()), "{:n}", 1234567);
// s == "1~234~567"

  • Constrained formatting functions on proper iterator types (fmtlib#921). Thanks @DanielaE.

  • Added make_printf_args and make_wprintf_args functions (fmtlib#934). Thanks @tnovotny.

  • Deprecated fmt::visit, parse_context, and wparse_context. Use fmt::visit_format_arg, format_parse_context, and wformat_parse_context instead.

  • Removed undocumented basic_fixed_buffer which has been superseded by the iterator-based API (fmtlib#873, fmtlib#902). Thanks @superfunc.

  • Disallowed repeated leading zeros in an argument ID:

    fmt::print("{000}", 42); // error

  • Reintroduced support for gcc 4.4.

  • Fixed compilation on platforms with exotic double (fmtlib#878).

  • Improved documentation (fmtlib#164, fmtlib#877, fmtlib#901, fmtlib#906, fmtlib#979). Thanks @kookjr, @DarkDimius and @HecticSerenity.

  • Added pkgconfig support which makes it easier to consume the library from meson and other build systems (fmtlib#916). Thanks @colemickens.

  • Various build improvements (fmtlib#909, fmtlib#926, fmtlib#937, fmtlib#953, fmtlib#959). Thanks @tchaikov, @luncliff, @AndreasSchoenle, @hotwatermorning and @Zefz.

  • Improved string_view construction performance (fmtlib#914). Thanks @gabime.

  • Fixed non-matching char types (fmtlib#895). Thanks @DanielaE.

  • Fixed format_to_n with std::back_insert_iterator (fmtlib#913). Thanks @DanielaE.

  • Fixed locale-dependent formatting (fmtlib#905).

  • Fixed various compiler warnings and errors (fmtlib#882, fmtlib#886, fmtlib#933, fmtlib#941, fmtlib#931, fmtlib#943, fmtlib#954, fmtlib#956, fmtlib#962, fmtlib#965, fmtlib#977, fmtlib#983, fmtlib#989). Thanks @Luthaf, @stevenhoving, @christinaa, @lgritz, @DanielaE, @0x8000-0000 and @liuping1997.

5.2.1 - 2018-09-21

  • Fixed visit lookup issues on gcc 7 & 8 (fmtlib#870). Thanks @medithe.
  • Fixed linkage errors on older gcc.
  • Prevented fmt/range.h from specializing fmt::basic_string_view (fmtlib#865, fmtlib#868). Thanks @hhggit.
  • Improved error message when formatting unknown types (fmtlib#872). Thanks @foonathan.
  • Disabled templated user-defined literals when compiled under nvcc (fmtlib#875). Thanks @CandyGumdrop.
  • Fixed format_to formatting to wmemory_buffer (fmtlib#874).

5.2.0 - 2018-09-13

5.1.0 - 2018-07-05

5.0.0 - 2018-05-21

4.1.0 - 2017-12-20

4.0.0 - 2017-06-27

3.0.2 - 2017-06-14

3.0.1 - 2016-11-01

3.0.0 - 2016-05-07

2.1.1 - 2016-04-11

2.1.0 - 2016-03-21

  • Project layout and build system improvements (https://github.com/fmtlib/fmt/pull/267):

    • The code have been moved to the cppformat directory. Including format.h from the top-level directory is deprecated but works via a proxy header which will be removed in the next major version.
    • C++ Format CMake targets now have proper interface definitions.
    • Installed version of the library now supports the header-only configuration.
    • Targets doc, install, and test are now disabled if C++ Format is included as a CMake subproject. They can be enabled by setting FMT_DOC, FMT_INSTALL, and FMT_TEST in the parent project.

    Thanks @niosHD.

2.0.1 - 2016-03-13

2.0.0 - 2015-12-01

General

Optimization

Distribution

Documentation

Fixes

1.1.0 - 2015-03-06

1.0.0 - 2015-02-05

0.12.0 - 2014-10-25

  • [Breaking] Improved separation between formatting and buffer management. Writer is now a base class that cannot be instantiated directly. The new MemoryWriter class implements the default buffer management with small allocations done on stack. So fmt::Writer should be replaced with fmt::MemoryWriter in variable declarations.

    Old code:

    fmt::Writer w;

    New code:

    fmt::MemoryWriter w;

    If you pass fmt::Writer by reference, you can continue to do so:

    void f(fmt::Writer &w);

    This doesn't affect the formatting API.

  • Support for custom memory allocators (https://github.com/fmtlib/fmt/issues/69)

  • Formatting functions now accept [signed char]{.title-ref} and [unsigned char]{.title-ref} strings as arguments (https://github.com/fmtlib/fmt/issues/73):

    auto s = format("GLSL version: {}", glGetString(GL_VERSION));

  • Reduced code bloat. According to the new benchmark results, cppformat is close to printf and by the order of magnitude better than Boost Format in terms of compiled code size.

  • Improved appearance of the documentation on mobile by using the Sphinx Bootstrap theme:

    Old New

0.11.0 - 2014-08-21

  • Safe printf implementation with a POSIX extension for positional arguments:

    fmt::printf("Elapsed time: %.2f seconds", 1.23);
fmt::printf("%1$s, %3$d %2$s", weekday, month, day);

  • Arguments of char type can now be formatted as integers (Issue https://github.com/fmtlib/fmt/issues/55):

    fmt::format("0x{0:02X}", 'a');

  • Deprecated parts of the API removed.

  • The library is now built and tested on MinGW with Appveyor in addition to existing test platforms Linux/GCC, OS X/Clang, Windows/MSVC.

0.10.0 - 2014-07-01

Improved API

  • All formatting methods are now implemented as variadic functions instead of using operator<< for feeding arbitrary arguments into a temporary formatter object. This works both with C++11 where variadic templates are used and with older standards where variadic functions are emulated by providing lightweight wrapper functions defined with the FMT_VARIADIC macro. You can use this macro for defining your own portable variadic functions:

    void report_error(const char *format, const fmt::ArgList &args) {
  fmt::print("Error: {}");
  fmt::print(format, args);
}
FMT_VARIADIC(void, report_error, const char *)

report_error("file not found: {}", path);

    Apart from a more natural syntax, this also improves performance as there is no need to construct temporary formatter objects and control arguments' lifetimes. Because the wrapper functions are very lightweight, this doesn't cause code bloat even in pre-C++11 mode.

  • Simplified common case of formatting an std::string. Now it requires a single function call:

    std::string s = format("The answer is {}.", 42);

    Previously it required 2 function calls:

    std::string s = str(Format("The answer is {}.") << 42);

    Instead of unsafe c_str function, fmt::Writer should be used directly to bypass creation of std::string:

    fmt::Writer w;
w.write("The answer is {}.", 42);
w.c_str();  // returns a C string

    This doesn't do dynamic memory allocation for small strings and is less error prone as the lifetime of the string is the same as for std::string::c_str which is well understood (hopefully).

  • Improved consistency in naming functions that are a part of the public API. Now all public functions are lowercase following the standard library conventions. Previously it was a combination of lowercase and CapitalizedWords. Issue https://github.com/fmtlib/fmt/issues/50.

  • Old functions are marked as deprecated and will be removed in the next release.

Other Changes

  • Experimental support for printf format specifications (work in progress):

    fmt::printf("The answer is %d.", 42);
std::string s = fmt::sprintf("Look, a %s!", "string");

  • Support for hexadecimal floating point format specifiers a and A:

    print("{:a}", -42.0); // Prints -0x1.5p+5
print("{:A}", -42.0); // Prints -0X1.5P+5

  • CMake option FMT_SHARED that specifies whether to build format as a shared library (off by default).

0.9.0 - 2014-05-13

  • More efficient implementation of variadic formatting functions.

  • Writer::Format now has a variadic overload:

    Writer out;
out.Format("Look, I'm {}!", "variadic");

  • For efficiency and consistency with other overloads, variadic overload of the Format function now returns Writer instead of std::string. Use the str function to convert it to std::string:

    std::string s = str(Format("Look, I'm {}!", "variadic"));

  • Replaced formatter actions with output sinks: NoAction -> NullSink, Write -> FileSink, ColorWriter -> ANSITerminalSink. This improves naming consistency and shouldn't affect client code unless these classes are used directly which should be rarely needed.

  • Added ThrowSystemError function that formats a message and throws SystemError containing the formatted message and system-specific error description. For example, the following code

    FILE *f = fopen(filename, "r");
if (!f)
  ThrowSystemError(errno, "Failed to open file '{}'") << filename;

    will throw SystemError exception with description "Failed to open file '<filename>': No such file or directory" if file doesn't exist.

  • Support for AppVeyor continuous integration platform.

  • Format now throws SystemError in case of I/O errors.

  • Improve test infrastructure. Print functions are now tested by redirecting the output to a pipe.

0.8.0 - 2014-04-14

  • Initial release