View source for Module:Protect/doc

{{Module rating|protected}}
{{used in system}}
This [[Help:Lua metamodules|metamodule]] simplifies error handling in other modules. It transforms a function, which may throw an error, into a function, which returns a specified error message in that case.

== Usage ==
<syntaxhighlight lang="lua">
 local protect = require('Module:Protect')
 local protectedFunc = protect(func, errFormat, options)
</syntaxhighlight>
=== Arguments ===

* ''{{code|func}}''
*: Function to be transformed.
* ''{{code|errFormat}}'' (default: {{code|'Error: %s'}})
*: Custom error message.
*: Use {{code|'%s'}} to include the message from a caught error.
* ''{{code|options}}'' – optional table with the following fields:
** {{code|raw}} (default: false)
**: If true, then ''{{code|errFormat}}'' will be used as is, otherwise it will be wrapped inside a tag <code><nowiki><strong class="error"></nowiki></code>.
** {{code|removeLocation}} (default: true)
**: If true, removes location information from caught error messages.

=== Return value ===

The resulting {{code|protectedFunc}} is a ''function'', which calls the original function ''{{code|func}}'', passing all arguments to it, and returns all its return values. If ''{{code|func}}'' throws an error, the specified error message is returned instead.

== Example ==
<syntaxhighlight lang="lua">
local protect = require('Module:Protect')

local p = {}

function p.main(frame)
    if not frame.args[1] then
        error('missing argument')
    end
    return frame.args[1]
end

p.main = protect(p.main)

return p
</syntaxhighlight>
Invoking the main function without arguments will output: <strong class="error">Error: missing argument</strong>
<includeonly>{{#ifeq:{{SUBPAGENAME}}|sandbox | |
[[Category:Error-handling modules]]
}}</includeonly>