Table of Contents
00000000:0001 - #IFEXT
Information
- ID: 00000000:0001
Flags
| Flag | Set? (MUST/MAY/…) | Description |
|---|---|---|
| parsing_must | MUST NOT | |
| reading_must | MUST NOT | |
| writing_must | MUST NOT | |
| playing_should | MAY | If any #IFEXT calls are used in Objects with the described caveat for optional support. |
| playing_must | MAY | If any #IFEXT calls are used in Objects. |
| editing_should | MUST NOT |
Field data
None.
Description
This extension adds an OOP command which faciliates run-time detection of extensions on both ZZT 3.2 and ZXT-compatible implementations. The command is #IFEXT owner_id selector_id …, where owner_id and selector_id are specified as 32-bit and 16-bit hexadecimal numbers, respectively. If the extension with a given owner_id and selector_id is currently active within the execution context, the rest of the line is treated as a command.
Keep in mind that to support #IFEXT as an optional extension, an :IFEXT label SHOULD be provided to handle the situation in which this extension is not present.
Example usage
Simple scenario
#ifext 00000000 0001 found :found Extensions found! #end :ifext Extensions not found. #end
Two touch codepaths
@Interactive #ifext 00000000 0001 zap touch :ifext #end :touch I found nothing... #end :touch I found IFEXT support! #end
Two touch codepaths (#BIND workaround)
If the code above is bound, :TOUCH might end up being zapped multiple times. This code takes care of that:
@Interactive #send init #end :init #zap init #ifext 00000000 0001 zap touch :ifext #end :touch I found nothing... #end :touch I found IFEXT support! #end
An alternative, more advanced technique is pre-setting the instruction pointer in an external editor.