Help:ParserFunctions

From Homestar Runner Wiki

Revision as of 00:05, 29 October 2007

This wiki has an extension installed, called ParserFunctions. Here's how to use them:

#expr:

{{#expr:}} solves mathematical expressions. It only works with numerical entries; if you want to use strings, see #ifeq.

#if:

The {{#if:}} function is an if-then-else system. If the condition string is empty, it returns the "else text". If it is not empty, it returns the "then text". The syntax is:

{{#if: <condition string> | <then text> | <else text> }}

Its most common usage is in templates, where if the user defines a parameter, then it returns some prescribed text. If the user does not specify the parameter, it returns a default. Example:

{{#if: {{{parameter|}}} | Parameter is defined | Parameter is not defined }}

If the user types {{templatename|parameter=true}} or something similar, the result is "Parameter is defined". However, if they type {{templatename}}, the result is "Parameter is not defined". Note in the above example that the expression is a special function that returns the value of the parameter if it has been defined and returns the text to the right of the vertical bar (|) if the parameter has not been defined.

{{#if:}} does not solve expressions. For example, if you type {{#if: 30 - 30 = 50 | 1 | 0 }}, the result will be 1, since 30 - 30 = 50 is not empty. If you want to do if-then-else using expressions, see #ifexpr.

#ifeq:

{{#ifeq:}} compares two strings and then performs an if-then-else process. To use:

{{#ifeq: <text 1> | <text 2> | <if equal> | <if not equal> }}

If text 1 and text 2 are equal, then it returns the <ifequal> text. Otherwise, it returns the <ifnotequal> text.

Some examples:

• {{#ifeq: {{NAMESPACE}} | Help | This page is in the Help Namespace | This page is not in the Help Namespace }} shows up as This page is in the Help Namespace.
• {{#ifeq: 7 | +000007.0 | Seven = Seven | Seven is not equal to Seven }} shows up as Seven = Seven

In this above example, notice that #ifeq can treat numbers as well as strings.

{{#ifeq:}} is case-sensitive:

{{#ifeq: capital | Capital | Equal | Not Equal }} shows up as Not Equal.

#ifexist:

{{#ifexist:}} performs an if-then-else process depending on whether a page exists. Syntax:

{{#ifexist: <page name> | <if exists> | <if does not exist> }}

{{#ifexist:}} does not work with interwiki links.

Example:

{{#ifexist: sbemail | [[Strong Bad Email]] | [[Main Page]] }} returns Strong Bad Email because a page named "sbemail" does exist.

#ifexpr:

{{#ifexpr:}} is an if-then-else routine that, like {{#expr:}}, can only be used with numbers. Syntax:

{{#ifexpr: <expression> | <if true> | <if false> }}

Some examples:

• {{#ifexpr: 30 / 40 = 120 | yes | no }} returns no.
• {{#ifexpr: {{PAGENAME}} = ParserFunctions | This is a help page | No}} returns Expression error: Unrecognised word "parserfunctions" because "ParserFunctions" (the text returned by {{PAGENAME}}) is a string, not a number.

#switch:

{{#switch:}} compares a number or a string against many items, and returns a result corresponding to the item it matches. Syntax:

{{#switch: <value>
| <result 1> = <text if 1 is true>
| <result 2> = <text if 2 is true>
| <result 3> = <text if 3 is true>
| <result 4> = <text if 4 is true>
| #default = <default value if none are true>
}}

If <value> matches <result 2>, for example, <text if 2 is true> will be returned by the function. If <value> does not match any of the first four items, <default value if none are true> will be returned.

"| <result n> = <text if n is true>" can be repeated as many times as necessary. However, "#default" can only be used once.

It is also possible to have "fall-through":

{{#switch: <value>
| <result 1>
| <result 2>
| <result 3> = <text if 1, 2, or 3 is true>
| <result 4> = <text if 4 is true>
| #default = <default value if none are true>
}}

<result 1> and <result 2> do not have equal signs, and if <value> matches either of them, the text corresponding to <result 3> will be returned.

#time:

{{#time:}} is used for time and date formatting. It can be used to show the current time or day, or a set time or day in a certain format. Either way, here are the codes (following UTC):

If any input other than those discussed above is provided, it will pass through the function unmodified. So, links and punctuation can be easily used with this function. Examples:

• {{#time: l j F Y }} generates Wednesday 4 February 2026.
• {{#time: m/Y }} generates 02/2026.
• {{#time: H:i | - 6 hours}} generates 05:02, 6 hours before the current time
• {{#time: l Y-m-d }} generates Wednesday 2026-02-04.
• {{#time: l }} generates Wednesday.
• {{#time: z | 20071031}} generates 303, Halloween day in "z" format

#rand:

{{#rand:}} generates a random integer. It has been deprecated in current versions of ParserFunctions, but the Homestar Runner Wiki currently uses an older version that still includes {{#rand:}}. Syntax:

{{#rand: <minimum> | <maximum> }}

The minimum is the smallest ineteger it can generate, the maximum is the largest.

Examples:

• {{#rand: 1 | 50 }} generates 45.
• {{#rand: 1 | 500000 }} generates 230958.
• {{#rand: -10 | -1 }} generates -3.
• {{#rand: .1 | .9 }} generates 0, because it rounds the magnitude of the input down to the nearest integer (in this example, both the minimum and maximum values are 0).

See Also

Meta's page on ParserFunctions