define: DUK_OPT_HAVE_CUSTOM_H
introduced: 1.0.0
deprecated: 1.3.0
tags:
  - portability
description: >
  Normally you define DUK_OPT_xxx feature options and the autodetecting
  duk_config.h (previously internal duk_features.h.in) header resolves
  these with platform/compiler constraints to determine effective compilation
  options for Duktape internals.  The effective options are provided as
  DUK_USE_xxx defines which you normally never see.

  If you define DUK_OPT_HAVE_CUSTOM_H, Duktape will include "duk_custom.h"
  after determining the appropriate DUK_USE_xxx defines but before compiling
  any code.  The duk_custom.h header, which you provide, can then tweak the
  active DUK_USE_xxx defines freely.  See duk_config.h and genconfig option
  metadata for the available defines.

  This approach is useful when the DUK_OPT_xxx feature options don't
  provide enough flexibility to tweak the build.  The downside is that you can
  easily create inconsistent DUK_USE_xxx flags, the customization header
  will be version specific, and you need to peek into Duktape internals to
  know what defines to tweak.

  NOTE: This option is deprecated.  The preferred method for customization
  starting from Duktape 1.3.0 is to create/modify a "duk_config.h" header.