$ListImg: Difference between revisions

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==Syntax==
==Syntax==
<p class="syntax">[%result =] $ListImg(list_identifier, image_id)
<p class="syntax">[<span class="term">%result</span> =] $ListImg(<span class="term">list_identifier</span>, <span class="term">image_id</span>)
</p>
</p>
<table>
<table>
<tr><th>%result</th>
<tr><th>%result</th>
<td>A string that contains a 0, or it contains a [[#Return codes|negative number]] if an error has occurred. </td></tr>
<td>A string that contains a 0, or it contains a negative number (see [[#Return codes|Return codes]]) if an error has occurred. </td></tr>


<tr><th>list_identifier</th>
<tr><th>list_identifier</th>
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<tr><th>image_id</th>
<tr><th>image_id</th>
<td>A string containing the name of an image, or it can be any image item from the required image. This is a required argument. </td></tr>
<td>A string containing the name of an image (or, as shown below in the [[#imageItem|Usage notes]], it can be an identifier of an image-item from the image). This is a required argument. </td></tr>
</table>
</table>


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==Usage notes==
==Usage notes==
<ul>
<ul>
<li>Suppose there is an image with the following description:
<li id="imageItem">Suppose there is an image with the following description:
<p class="code">IMAGE SALES
<p class="code">IMAGE SALES
ITEM IS STRING LEN 16
ITEM IS STRING LEN 16

Latest revision as of 20:51, 12 June 2018

Associate an image with a $list

Note: Many $functions have been deprecated in favor of Object Oriented methods. The OO equivalent for the $ListImg function is BindImage.

The $ListImg function accepts two arguments and returns a numeric result: a 0 (indicating that the image has been associated with the $list) or a negative number (indicating that an error has occurred). It is a callable $function.


Syntax

[%result =] $ListImg(list_identifier, image_id)

%result A string that contains a 0, or it contains a negative number (see Return codes) if an error has occurred.
list_identifier A $list identifier. This is a required argument.
image_id A string containing the name of an image (or, as shown below in the Usage notes, it can be an identifier of an image-item from the image). This is a required argument.

Return codes

-5 - Required argument not specified -6 - $List identifier invalid -8 - Image not found

Usage notes

  • Suppose there is an image with the following description:

    IMAGE SALES ITEM IS STRING LEN 16 ID IS STRING LEN 8 PRICE IS BINARY LEN 4 END IMAGE

    One can associate this image with the $list %list with:

    %rc = $ListImg(%list, 'SALES')

    or

    %rc = $ListImg(%list, %SALES:ID)

    While the latter is syntactically inefficient (:ID is superfluous), it is more efficient because the image name hashing and lookup is done at compile time rather than evaluation time.

  • Functions that can use the association between an image and a $list are:
  • The association between an image and a $list is an association between the image and the particular $list identifier value. A $ListMove does not change the image association of the target $list, and the image association of a $list is not saved or restored with $ListSav and $ListRst.

Products authorizing $ListImg