PBInvoke library

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Summary

PBInvoke is a PowerBuilder library for calling external DLL functions with arbitrary parameter and return types - structures, unions, pointers, etc. including function pointers to PowerBuilder methods callable from DLL code as callbacks.

PBInvoke goals

Allow PowerBuilder developers to work in PowerScript with complex data structures without writing wrapper DLLs in other languages such as C/C++.
Make declarations of external functions ANSI/Unicode-independent which avoids migration issues when using the same code across ANSI and Unicode versions of PowerBuilder.
Support any C/C++ data type (except classes). This includes complex nested data types involving structs, unions, pointers, simple types and their combinations.
Support not only STDCALL calling convention, but also CDECL which is default in C/C++ programs.
Allow PB code to be called from external functions as callbacks with full access to passed parameters.
Support wide range of PowerBuilder versions from PB 6 to PB 11.5 and any future version.

Why not use native PowerBuilder external functions?

PowerBuilder support of external functions has the following restrictions which make developers write wrapper code in C/C++ and compile it with third party compilers.

No support for PowerBuilder callbacks.
No support for unions and pointers to complex data types in structures.
External function declarations depend on string encoding expected by functions. Often a charset conversion is required between ANSI PB and Unicode DLL and vice versa. PowerScript attrubute ';ansi' is available only in PB10+ and makes the source code incompatible with older PB versions. PBInvoke automatically handles the encoding stuff (including function name suffixes such as A/W in WinAPI).

Why not use PowerBuilder extensions (PBNI)?

PBNI is available only as of PB9.
PBNI requires knowledge of C++.
PBNI extensions are quite hard to write and debug.
PBNI requires separate DLLs for ANSI and Unicode versions.