Christophe CapMike Jackson$Revision: 1.5 $

This TIP alters Tcl to allow embedded uses of the Tcl library (and any extensions) to either use the Tcl memory allocators as their main allocator (especially in C++) or to set the memory allocator that Tcl uses for itself through ckalloc().

A while ago I was experiencing troubles when allocating images ([image create photo]) while memory was already exhausted, my app crashed (due to known bug item #698571, which is in the HEAD by now!) This shouldn't happen anyway since my application had it's new handler set. Tracing down the source of the allocators I noticed that Tcl uses HeapAlloc() (on Win32) to allocate its memory. Why not use malloc()?

It would be nice to be able to catch memory allocation errors with a custom new handler. A solution could be to replace HeapAlloc() (on Win32) and other platform specific memory handlers should be replaced by malloc(). This way a new handler can by set through set_new_handler(). Note that the Microsoft VC++ compiler has some ANSI incompatibility in that it uses _set_new_handler() rather than set_new_handler(). We would naturally conceal this platform difference. For example: I2luY2x1ZGUgPG5ldz4gLy8=Ly8gTmV3IGhhbmRsZXIgZm9yIE1pY3Jvc29mdCBWaXN1YWwgQysrIGNvbXBpbGVyLy8=I2lmZGVmIF9NU0NfVkVSI2luY2x1ZGUgPG5ldy5oPg==aW50IF9fY2RlY2wgX25ld0hhbmRsZXIoc2l6ZV90IHNpemUgKQ==ew==ICAgLy8gRG8gd2hhdGV2ZXI=ICAgcmV0dXJuIDA7fQ==I2Vsc2U=Ly8=Ly8gQW5zaSBDL0MrKyBuZXcgaGFuZGxlcg==Ly8=dm9pZCBfX2NkZWNsIF9uZXdIYW5kbGVyKCB2b2lkICk=ew==ICAgLy8gRG8gd2hhdGV2ZXI=fQ==I2VuZGlmdm9pZCBzZXRoYW5kbGVycyh2b2lkKQ==ew==Ly8gTWljcm9zb2Z0IGNvbXBpbGVyIA==I2lmZGVmIF9NU0NfVkVSICA=ICAgX3NldF9uZXdfaGFuZGxlciAoX25ld0hhbmRsZXIpOyAvLyBTZXR1cCBuZXcgaGFuZGxlcg==ICAgX3NldF9uZXdfbW9kZSggMSApOyAvLyBSZS1yb3V0ZSBtYWxsb2MgZmFpbHVyZXMgdG8gbmV3IGhhbmRsZXIgIQ==Ly8gQW5zaSBjb21waWxlciA=I2Vsc2UgICAgc2V0X25ld19oYW5kbGVyIChfbmV3SGFuZGxlcik7IC8vIEFOU0kgbmV3IGhhbmRsZXI=I2VuZGlmfQ==

The above suggested solution could work for some compilers, but may not for all (some compilers might not support setting a malloc failure callback.) Therefore a Tcl custom new handler functionality could be implemented that handles Tcl specific memory allocation failures. Something like: Tcl_SetMemHandler()?

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