pykd

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import pykd
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#it's exact name of the std::string class. We need it later.
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stringClassName = "basic_string<char,std::char_traits<char>,std::allocator<char> >"
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fullStringClassName = "std::" + stringClassName
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# get a malloc function. May be we have not its prototype in pdb file, so we need to define prototype manually
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PVoid = pykd.typeInfo("Void*")
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size_t = pykd.typeInfo("Int8B") if pykd.getCPUMode() == pykd.CPUType.AMD64 else pykd.typeInfo("Int4B")
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mallocProto = pykd.defineFunction( PVoid, pykd.callingConvention.NearC )
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mallocProto.append("size", size_t)
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malloc = pykd.typedVar(mallocProto, pykd.getOffset("malloc") ) #getOffset("malloc") may take a long time
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# get a type of a std::string
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stringClass = pykd.typeInfo(fullStringClassName)
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# allocate memory
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buffer = malloc( stringClass.size() )
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# get a typed access to memory. As you may see the instance of the std::string is not initialized
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stringVar = pykd.typedVar( stringClass, buffer )
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# set up parameters for a constructor call.
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param = pykd.stackAlloc(100)
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pykd.writeCStr(param, "hello")
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# call ctor for initalizing. std::string has several forms of constructor so we need to note prototype
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ctor = stringVar.method( stringClassName, "Void(__thiscall)(Char*)" )
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ctor(param)
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#check result:
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print( pykd.loadCStr( stringVar.c_str() ) ) 
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pykd.stackFree(100)
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