File: gawk.info,  Node: Old Extension Problems,  Next: Extension New Mechanism Goals,  Up: Extension Design

C.5.1 Problems With The Old Mechanism
-------------------------------------

The old extension mechanism had several problems:

   * It depended heavily upon 'gawk' internals.  Any time the 'NODE'
     structure(1) changed, an extension would have to be recompiled.
     Furthermore, to really write extensions required understanding
     something about 'gawk''s internal functions.  There was some
     documentation in this Info file, but it was quite minimal.

   * Being able to call into 'gawk' from an extension required linker
     facilities that are common on Unix-derived systems but that did not
     work on MS-Windows systems; users wanting extensions on MS-Windows
     had to statically link them into 'gawk', even though MS-Windows
     supports dynamic loading of shared objects.

   * The API would change occasionally as 'gawk' changed; no
     compatibility between versions was ever offered or planned for.

   Despite the drawbacks, the 'xgawk' project developers forked 'gawk'
and developed several significant extensions.  They also enhanced
'gawk''s facilities relating to file inclusion and shared object access.

   A new API was desired for a long time, but only in 2012 did the
'gawk' maintainer and the 'xgawk' developers finally start working on it
together.  More information about the 'xgawk' project is provided in
*note gawkextlib::.

   ---------- Footnotes ----------

   (1) A critical central data structure inside 'gawk'.