Add option for extra_args to solc invocation

Since `compile()` has a `**kwargs` at the end we can easily add an
optional `extra_args` argument to all the compiler calls.

We for example need this if we would like to specify specific locations
on the system path where contracts can be imported from.

Author: LefterisJP

ethereum/_solidity.py

@@ -40,11 +40,12 @@ def get_solidity():
     return solc_wrapper
 
 
-def solc_arguments(libraries=None, combined='bin,abi', optimize=True):
+def solc_arguments(libraries=None, combined='bin,abi', optimize=True, extra_args=''):
     """ Build the arguments to call the solc binary. """
     args = [
         '--combined-json', combined,
         '--add-std',
+        extra_args
     ]
 
     if optimize:
@@ -221,7 +222,7 @@ def solidity_unresolved_symbols(hex_code):
     return set(re.findall(r"_.{39}", hex_code))
 
 
-def compile_file(filepath, libraries=None, combined='bin,abi', optimize=True):
+def compile_file(filepath, libraries=None, combined='bin,abi', optimize=True, extra_args=''):
     """ Return the compile contract code.
 
     Args:
@@ -236,7 +237,7 @@ def compile_file(filepath, libraries=None, combined='bin,abi', optimize=True):
 
     workdir, filename = os.path.split(filepath)
 
-    args = solc_arguments(libraries=libraries, combined=combined, optimize=optimize)
+    args = solc_arguments(libraries=libraries, combined=combined, optimize=optimize, extra_args=extra_args)
     args.insert(0, get_compiler_path())
     args.append(filename)
 
@@ -245,18 +246,19 @@ def compile_file(filepath, libraries=None, combined='bin,abi', optimize=True):
     return solc_parse_output(output)
 
 
-def compile_contract(filepath, contract_name, libraries=None, combined='bin,abi', optimize=True):
+def compile_contract(filepath, contract_name, libraries=None, combined='bin,abi', optimize=True, extra_args=''):
     all_contracts = compile_file(
         filepath,
         libraries=libraries,
         combined=combined,
         optimize=optimize,
+        extra_args=extra_args
     )
 
     return all_contracts[contract_name]
 
 
-def compile_last_contract(filepath, libraries=None, combined='bin,abi', optimize=True):
+def compile_last_contract(filepath, libraries=None, combined='bin,abi', optimize=True, extra_args=''):
     with open(filepath) as handler:
         all_names = solidity_names(handler.read())
 
@@ -273,11 +275,12 @@ def compile_last_contract(filepath, libraries=None, combined='bin,abi', optimize
         libraries=libraries,
         combined=combined,
         optimize=optimize,
+        extra_args=extra_args
     )
 
 
-def compile_code(sourcecode, libraries=None, combined='bin,abi', optimize=True):
-    args = solc_arguments(libraries=libraries, combined=combined, optimize=optimize)
+def compile_code(sourcecode, libraries=None, combined='bin,abi', optimize=True, extra_args=''):
+    args = solc_arguments(libraries=libraries, combined=combined, optimize=optimize, extra_args=extra_args)
     args.insert(0, get_compiler_path())
 
     process = subprocess.Popen(args, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
@@ -297,17 +300,17 @@ class Solc(object):
     compiler_version = staticmethod(compiler_version)
 
     @staticmethod
-    def _code_or_path(sourcecode, path, contract_name, libraries, combined):
+    def _code_or_path(sourcecode, path, contract_name, libraries, combined, extra_args):
         warnings.warn('solc_wrapper is deprecated, please use the functions compile_file or compile_code')
 
         if sourcecode and path:
             raise ValueError('sourcecode and path are mutually exclusive.')
 
         if path and contract_name:
-            return compile_contract(path, contract_name, libraries=libraries, combined=combined)
+            return compile_contract(path, contract_name, libraries=libraries, combined=combined, extra_args=extra_args)
 
         if path:
-            return compile_last_contract(path, libraries=libraries, combined=combined)
+            return compile_last_contract(path, libraries=libraries, combined=combined, extra_args=extra_args)
 
         all_names = solidity_names(sourcecode)
         all_contract_names = [
@@ -316,20 +319,20 @@ def _code_or_path(sourcecode, path, contract_name, libraries, combined):
         ]
         last_contract = all_contract_names[-1]
 
-        result = compile_code(sourcecode, libraries=libraries, combined=combined)
+        result = compile_code(sourcecode, libraries=libraries, combined=combined, extra_args=extra_args)
         return result[last_contract]
 
     @classmethod
-    def compile(cls, code, path=None, libraries=None, contract_name=''):
+    def compile(cls, code, path=None, libraries=None, contract_name='', extra_args=''):
         """ Return the binary of last contract in code. """
-        result = cls._code_or_path(code, path, contract_name, libraries, 'bin')
+        result = cls._code_or_path(code, path, contract_name, libraries, 'bin', extra_args)
         return result['bin']
 
     @classmethod
-    def mk_full_signature(cls, code, path=None, libraries=None, contract_name=''):
+    def mk_full_signature(cls, code, path=None, libraries=None, contract_name='', extra_args=''):
         "returns signature of last contract in code"
 
-        result = cls._code_or_path(code, path, contract_name, libraries, 'abi')
+        result = cls._code_or_path(code, path, contract_name, libraries, 'abi', extra_args)
         return result['abi']
 
     @classmethod