python - Create object from string repesentation in C API -

i working on system embedding python interpreter, , need construct pyobject* given string c api.

i have const char* representing dictionary, in proper format eval() work within python, ie: "{'bar': 42, 'baz': 50}".

currently, being passed python pyobject* using py_unicode_ api (representing string), in python interpreter, can write:

foo = eval(myobject.value) print(foo['bar']) # prints 42 

i change automatically "eval" const char* on c side, , return pyobject* representing completed dictionary. how go converting string dictionary in c api?

there 2 basic ways this.

the first call eval same way in python. trick need handle builtins module, because don't free in c api. there number of ways this, 1 easy way import it:

/* or pyeval_getbuiltins() if know you're @ interpreter's top level */ pyobject *builtins = pyimport_importmodule("builtins"); pyobject *eval = pyobject_getattrstring(builtins, "eval"); pyobject *args = py_buildvalue("(s)", expression_as_c_string); pyobject *result = pyobject_call(eval, args); 

(this untested code, , @ least leaks references, , doesn't check null return if want handle exceptions on c side… should enough idea across.)

one nice thing can use ast.literal_eval in same way eval (which means free validation); change "builtins" "ast", , "eval" "literal_eval". real win you're doing eval in python, know wanted.

the alternative use compilation apis. @ high level, can build python statement out of "foo = eval(%s)" , pyrun_simplestring it. below that, use py_compilestring parse , compile expression (you can parse , compile in separate steps, isn't useful here), pyeval_evalcode evaluate in appropriate globals , locals. (if you're not tracking globals yourself, use interpreter-reflection apis pyeval_getlocals , pyeval_getglobals.) note i'm giving super-simplified version of each function; want use 1 of sibling functions. can find them in docs.