[Xapian-tickets] [Xapian] #800: Supporting sub-routine in OmegaScript

[Xapian]

#800: Supporting sub-routine in OmegaScript
--------------------------+-------------------------------
 Reporter:  Gaurav Arora  |             Owner:  Olly Betts
     Type:  enhancement   |            Status:  new
 Priority:  normal        |         Milestone:
Component:  Omega         |           Version:
 Severity:  normal        |        Resolution:
 Keywords:                |        Blocked By:
 Blocking:                |  Operating System:  All
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Changes (by Olly Betts):

 * type:  defect => enhancement
 * component:  Other => Omega

Comment:

 We already have "macros" - I guess you searched for "function" and didn't
 spot these?  Perhaps we should note in the docs they offer a "function-
 like" feature or something like that.

 {{{
 $def{MACRONAME,VALUE}
         define a macro which can take 0 to 9 arguments.  You can call it
 with
         ``$MACRONAME`` (if it take 0 arguments) or
         ``$MACRONAME{ARG1,ARG2,ARG3}`` is it takes arguments.  In value,
         arguments are available as ``$1``, ``$2``, ...  ``$9``.  In the
 current
         implementation, macros can override OmegaScript commands, but this
         shouldn't be relied on.  It's recommended to use capitalised names
 for
         macros to avoid collision with future OmegaScript commands.
 }}}

 E.g. you can do:

 {{{
 $def{PRETTYLIST,$list{$map{$1,$lower{$_}},$. }.}

 $PRETTYLIST{$cgilist{FOO}}

 $PRETTYLIST{$cgilist{BAR}}
 }}}

 It seems you're thinking to pass parameters via `$set{...}` which seems
 less nice than being able to call a macro with parameters just like you'd
 call a built-in !OmegaScript command.

 Is there anything you need that macros don't offer?

 The main limitations are probably that they don't currently support lazy
 evaluation, and there's no checking for the number of arguments passed.
 The mechanisms for these exist as macros use the same machinery as built-
 in commands - the hardest part is probably coming up a clean way to
 specify them when defining a macro.
-- 
Ticket URL: <https://trac.xapian.org/ticket/800#comment:2>
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