IOBuf::toString()

Summary:
`to<std::string>()` becomes awkward in templates, if called on an object with dependent type it needs to be invoked as `obj->template to<std::string>()`.

Since 99.999% of the use cases for `to()` are with `std::string`, add a convenience non-template method.

Reviewed By: ilvokhin

Differential Revision: D58672590

fbshipit-source-id: 6aeddff43feef1bd0587aadeda1f51a59e7d93ae

Author: ot

folly/io/IOBuf.h

@@ -28,6 +28,7 @@
 #include <iterator>
 #include <limits>
 #include <memory>
+#include <string>
 #include <type_traits>
 
 #include <glog/logging.h>
@@ -1787,17 +1788,24 @@ class IOBuf {
   void appendTo(Container& container) const;
 
   /**
-   * Dump the chain data into a container.
+   * Returns a container containing the chain data.
    *
    * @copydetails appendTo(Container&) const
    *
    * @tparam Container  The type of container to return.
    *
-   * @returns  A Container whose data equals the coalseced data of this chain
+   * @returns  A Container whose data equals the coalesced data of this chain
    */
   template <class Container>
   Container to() const;
 
+  /**
+   * Convenience version of to<std::string>() that works when called
+   * on a dependent name in a template function without having to use
+   * the "template" keyword.
+   */
+  std::string toString() const { return to<std::string>(); }
+
   /**
    * Get an iovector suitable for e.g. writev()
    *

folly/io/test/IOBufTest.cpp

@@ -1805,6 +1805,7 @@ TEST(IOBuf, AppendTo) {
 
   IOBuf buf;
   EXPECT_EQ(buf.to<std::string>(), "");
+  EXPECT_EQ(buf.toString(), "");
 
   auto temp = &buf;
   temp->insertAfterThisOne(IOBuf::copyBuffer("Hello"));