System Variable LX - Revision history

Robert Wallick: expanded, added example

2015-07-15T18:09:48Z

expanded, added example

← Older revision		Revision as of 14:09, 15 July 2015
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	<h1>{quad}LX - Latent Expression</h1>		<h1>{quad}LX - Latent Expression</h1>
	{{BoxStart\|<apll>Z←⎕LX</apll>		{{BoxStart\|<apll>Z←⎕LX</apll>
	\| returns the current value of the Latent eXpression. }}		\| user query of <apll>⎕LX</apll> returns the current value of the Latent eXpression or initial workspace startup/load value. }}
	{{BoxEnd\|<apll>Z</apll> is a string containing the current value of ⎕LX, and is null if {quad}LX is not defined. ~~This~~ is the command to execute when the workspace is loaded ~~with~~ )LOAD.}}<br/>		{{BoxEnd\|Returned by APL's Interpreter:   <apll>Z</apll>   is a string containing the current value of ⎕LX, and is null if {quad}LX is not defined, i.e. set to

			<apll>''</apll>, a null string. <apll>⎕LX</apll>'s value is the command to execute when the workspace is next loaded(after pre-Saving of course) - using )LOAD.}}<br/>

	{\| border="1" cellpadding="5" cellspacing="0" rules="none" summary=""		{\| border="1" cellpadding="5" cellspacing="0" rules="none" summary=""
	\|\| <apll>⎕LX←'START'</apll> \|\| Have the workspace execute function START when it is loaded via )LOAD or the '''<u>F</u>ile, <u>O</u>pen''' menu		\|\| <apll>⎕LX←'START'</apll> \|\| Have the workspace execute function START when it is loaded via )LOAD or the '''<u>F</u>ile, <u>O</u>pen''' menu
	\|-		\|-
	\| valign="top" \|<apll>⎕LX←''</apll> \|\| Do not have any function execute when the workspace is loaded (this is the default).		\| valign="top" \|<apll>⎕LX←''</apll> \|\| Do not have any function execute when the workspace is loaded (null string, this is the default).
	\|-		\|-
	\|}		\|}
	<br />		<br />

	~~The~~ {quad}LX variable is used within a workspace to set ~~the~~ action to take when the workspace is loaded via )LOAD or the '''<u>F</u>ile, <u>O</u>pen''' menu. ~~Typically~~ {quad}LX is set to the name of a function in the workspace. {quad}LX defaults to null.		APL's <apll>{quad}LX</apll> system variable is used within a workspace to set action to take when the workspace is loaded via )LOAD or the '''<u>F</u>ile, <u>O</u>pen'''

			menu. Frequently {quad}LX is set to the name of a function in the workspace. {quad}LX defaults to null.

			<br><hr align="center" color="black" size="2" width="58%">

	~~Example usage~~:		<br><u>'''Sample use #1'''</u> - '''running a startup function''' when workspace is first loaded:
	:'''<big><code> {quad}LX{:=}'Start'</code></big>'''		:'''<big><code> {quad}LX{:=}'Start'</code></big>'''

	When this workspace is saved, the next time it is loaded through the <big>''')LOAD'''</big> command or the '''<u>F</u>ile, <u>O</u>pen''' menu, it will attempt to start the function <big>'''Start'''</big>. An error will occur if the function named in <big>'''{quad}LX'''</big> is not present when the workspace is loaded.		When this workspace is saved, the next time it is loaded through the <big>''')LOAD'''</big> command or the '''<u>F</u>ile, <u>O</u>pen''' menu, it will attempt to start the

			function <big>'''Start'''</big>. An error will occur if the function named in <big>'''{quad}LX'''</big> is not present when the workspace is loaded.

			The <big>'''{quad}LX'''</big> function is ''not'' executed if the workspace is loaded via the <apll>)XLOAD</apll> command or through the '''<u>F</u>ile, <u>X</u>load'''

			menu.

			The function of {quad}LX is similar to the function of the AUTOEXEC.BAT file when DOS is started, or when in Windows if you have a shortcut in the Startup Folder in the

			Start Menu. The function or action in the {quad}LX system variable is executed before the Session Manager returns control to you.

			The action of <big>'''{quad}LX'''</big> when a workspace is <apll>)LOAD</apll>ed is essentially equivalent to typing <big>'''{execute}{quad}LX'''</big> immediately after

			loading the workspace.

			Note that system commands beginning with a <big>''')'''</big> cannot be executed through <big><b>{quad}LX</b></big>. This is different from the APL Standard, for a reason.

			This variation from standard <u>prevents endless loops</u>, such as if a workspace named <big>'''loop'''</big> had a {quad}LX value of <big>''')load loop'''</big>.

			<br><hr align="center" color="black" size="2" width="58%">

			<br><u>'''Sample use #2'''</u> - '''displaying a user-introductory message using a global variable's value''' when the workspace is loaded:
			:'''<big><code> {quad}LX{:=}'⎕←Description' ⍝ Where Description is a global string variable in either vector or character matrix format.</code></big>'''

			<pre>
			Description←'Welcome APL User! Welcome to NARS, we speak APL here!'
			⍴Description ⍝ Query the shape of workspace global variable Description
			54
			⎕LX←'⎕←Description' ⍝ Notice use of the prompt or quad symbol and assignment arrow in front of the variable's name(⎕←), with APL's entire phrase in quotes.
			⎕LX ⍝ Query what is stored in system variable ⎕LX
			⎕←Description
			)SAVE ⍝ Save current workspace

			...
			⍝ APL workspace reloaded using )LOAD, startup message shown below:

	~~The <big>'''{quad}LX'''</big> function is ''not'' executed if the workspace is loaded via the <apll>)XLOAD</apll> command or through the '''<u>F</u>ile, <u>X</u>load''' menu.~~

	~~The function of {quad}LX is similar~~ to ~~the function of the AUTOEXEC.BAT file when DOS is started~~, ~~or when in Windows if you have a shortcut in the Startup Folder in the Start Menu. The function or action in the {quad}LX system variable is executed before the Session Manager returns control to you.~~		Welcome APL User! Welcome to NARS, we speak APL here!
			</pre>

	The ~~action of~~ <~~big~~>~~'''{quad}LX'''~~</~~big~~> ~~when a~~ workspace is <~~apll~~>~~)LOAD~~</~~apll~~>~~ed is essentially equivalent~~ to ~~typing <big>'''{execute}{quad}LX'''</big> immediately~~ after ~~loading the workspace~~.		The above <apll>⎕LX</apll> examples are helpful, both as workspace reminders <u>and or</u> to help unfamiliar users quickly get started using that particular APL workspace. If you were last editing a function just before )OFF, you can remind yourself where you were at, for example after a long week-end or you were in a complex debug situation. See also [[System_Command_SI\|State Indicator - system command )SI]].

	~~Note that system commands beginning with a~~ <~~big~~>~~''')'''~~<~~/big~~> cannot be executed through <big><b>{quad}LX</b></big>. This is different from the APL Standard. This (lack of) functionality prevents endless loops, such as if a workspace named <big>'''loop'''</big> had a {quad}LX value of <big>''')load loop'''</big>.		<br><hr align="center" color="gray" size="2" width="65%">

	==See Also==		==See Also==

Paul Robinson at 13:24, 13 March 2013

2013-03-13T13:24:19Z

← Older revision		Revision as of 09:24, 13 March 2013
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	<h1>{quad}LX - Latent Expression</h1>		<h1>{quad}LX - Latent Expression</h1>
			{{BoxStart\|<apll>Z←⎕LX</apll>
			\| returns the current value of the Latent eXpression. }}
			{{BoxEnd\|<apll>Z</apll> is a string containing the current value of ⎕LX, and is null if {quad}LX is not defined. This is the command to execute when the workspace is loaded with )LOAD.}}<br/>

	The {quad}LX variable is used within a workspace to set the action to take when the workspace is loaded via )LOAD or the '''~~File~~, ~~Open~~''' menu. Typically {quad}LX is set to the name of a function in the workspace. {quad}LX defaults to null.		{\| border="1" cellpadding="5" cellspacing="0" rules="none" summary=""
			\|\| <apll>⎕LX←'START'</apll> \|\| Have the workspace execute function START when it is loaded via )LOAD or the '''<u>F</u>ile, <u>O</u>pen''' menu
			\|-
			\| valign="top" \|<apll>⎕LX←''</apll> \|\| Do not have any function execute when the workspace is loaded (this is the default).
			\|-
			\|}
			<br />

			The {quad}LX variable is used within a workspace to set the action to take when the workspace is loaded via )LOAD or the '''<u>F</u>ile, <u>O</u>pen''' menu. Typically {quad}LX is set to the name of a function in the workspace. {quad}LX defaults to null.

	Example usage:		Example usage:
	:'''<big><code> {quad}LX{:=}'Start'</code></big>'''		:'''<big><code> {quad}LX{:=}'Start'</code></big>'''

	When this workspace is saved, the next time it is loaded through the <big>''')LOAD'''</big> command or the '''~~file~~, ~~open~~''' menu, it will attempt to start the function <big>'''Start'''</big>. An error will occur if the function named in <big>'''{quad}LX'''</big> is not present when the workspace is loaded.		When this workspace is saved, the next time it is loaded through the <big>''')LOAD'''</big> command or the '''<u>F</u>ile, <u>O</u>pen''' menu, it will attempt to start the function <big>'''Start'''</big>. An error will occur if the function named in <big>'''{quad}LX'''</big> is not present when the workspace is loaded.

	The <big>'''{quad}LX'''</big> function is ''not'' executed if the workspace is loaded via the <apll>)XLOAD</apll> command or through the '''~~file~~, ~~xload~~''' menu.		The <big>'''{quad}LX'''</big> function is ''not'' executed if the workspace is loaded via the <apll>)XLOAD</apll> command or through the '''<u>F</u>ile, <u>X</u>load''' menu.

	The function of {quad}LX is similar to the function of the AUTOEXEC.BAT file when DOS is started, or when in Windows if you have a shortcut in the Startup Folder in the Start Menu. The function or action in the {quad}LX system variable is executed before the Session Manager returns control to you.		The function of {quad}LX is similar to the function of the AUTOEXEC.BAT file when DOS is started, or when in Windows if you have a shortcut in the Startup Folder in the Start Menu. The function or action in the {quad}LX system variable is executed before the Session Manager returns control to you.
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	The action of <big>'''{quad}LX'''</big> when a workspace is <apll>)LOAD</apll>ed is essentially equivalent to typing <big>'''{execute}{quad}LX'''</big> immediately after loading the workspace.		The action of <big>'''{quad}LX'''</big> when a workspace is <apll>)LOAD</apll>ed is essentially equivalent to typing <big>'''{execute}{quad}LX'''</big> immediately after loading the workspace.

	Note that system commands beginning with a <big>''')'''</big> cannot be executed through <big><b>{quad}LX</b></big>. This prevents endless loops, such as if a workspace named <big>'''loop'''</big> had a {quad}LX value of <big>''')load loop'''</big>.		Note that system commands beginning with a <big>''')'''</big> cannot be executed through <big><b>{quad}LX</b></big>. This is different from the APL Standard. This (lack of) functionality prevents endless loops, such as if a workspace named <big>'''loop'''</big> had a {quad}LX value of <big>''')load loop'''</big>.

	==See Also==		==See Also==
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	{{System Variables}}		{{System Variables}}
			{{Article footer}}

Paul Robinson at 20:52, 27 February 2013

2013-02-27T20:52:43Z

← Older revision		Revision as of 16:52, 27 February 2013
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	The action of <big>'''{quad}LX'''</big> when a workspace is <apll>)LOAD</apll>ed is essentially equivalent to typing <big>'''{execute}{quad}LX'''</big> immediately after loading the workspace.		The action of <big>'''{quad}LX'''</big> when a workspace is <apll>)LOAD</apll>ed is essentially equivalent to typing <big>'''{execute}{quad}LX'''</big> immediately after loading the workspace.

	Note that system commands beginning with a <big>~~<b>~~)~~</b>~~</big> cannot be executed through <big><b>{quad}LX</b></big>.		Note that system commands beginning with a <big>''')'''</big> cannot be executed through <big><b>{quad}LX</b></big>. This prevents endless loops, such as if a workspace named <big>'''loop'''</big> had a {quad}LX value of <big>''')load loop'''</big>.

	==See Also==		==See Also==

Paul Robinson at 20:48, 27 February 2013

2013-02-27T20:48:31Z

← Older revision		Revision as of 16:48, 27 February 2013
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	<h1>{quad}LX - Latent Expression</h1>		<h1>{quad}LX - Latent Expression</h1>

	The {quad}LX variable is used within a workspace to set the action to take when the workspace is loaded. Typically it is set to the name of a function in the workspace. {quad}LX defaults to null.		The {quad}LX variable is used within a workspace to set the action to take when the workspace is loaded via )LOAD or the '''File, Open''' menu. Typically {quad}LX is set to the name of a function in the workspace. {quad}LX defaults to null.

	Example usage:		Example usage:
	:<code> {quad}LX{:=}'Start'</code>		:'''<big><code> {quad}LX{:=}'Start'</code></big>'''

	When this workspace is saved, the next time it is loaded, it will attempt to start the function '''Start'''. An error will occur if the function named in {quad}LX is not present when the workspace is loaded.		When this workspace is saved, the next time it is loaded through the <big>''')LOAD'''</big> command or the '''file, open''' menu, it will attempt to start the function <big>'''Start'''</big>. An error will occur if the function named in <big>'''{quad}LX'''</big> is not present when the workspace is loaded.

			The <big>'''{quad}LX'''</big> function is ''not'' executed if the workspace is loaded via the <apll>)XLOAD</apll> command or through the '''file, xload''' menu.

	The function of {quad}LX is similar to the function of the AUTOEXEC.BAT file when DOS is started, or when in Windows if you have a shortcut in the Startup Folder in the Start Menu. The function or action in the {quad}LX system variable is executed before the Session Manager returns control to you.		The function of {quad}LX is similar to the function of the AUTOEXEC.BAT file when DOS is started, or when in Windows if you have a shortcut in the Startup Folder in the Start Menu. The function or action in the {quad}LX system variable is executed before the Session Manager returns control to you.

			The action of <big>'''{quad}LX'''</big> when a workspace is <apll>)LOAD</apll>ed is essentially equivalent to typing <big>'''{execute}{quad}LX'''</big> immediately after loading the workspace.

	Note that system commands beginning with a <big><b>)</b></big> cannot be executed through <big><b>{quad}LX</b></big>.		Note that system commands beginning with a <big><b>)</b></big> cannot be executed through <big><b>{quad}LX</b></big>.

Paul Robinson at 20:40, 27 February 2013

2013-02-27T20:40:09Z

← Older revision		Revision as of 16:40, 27 February 2013
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	When this workspace is saved, the next time it is loaded, it will attempt to start the function '''Start'''. An error will occur if the function named in {quad}LX is not present when the workspace is loaded.		When this workspace is saved, the next time it is loaded, it will attempt to start the function '''Start'''. An error will occur if the function named in {quad}LX is not present when the workspace is loaded.

			The function of {quad}LX is similar to the function of the AUTOEXEC.BAT file when DOS is started, or when in Windows if you have a shortcut in the Startup Folder in the Start Menu. The function or action in the {quad}LX system variable is executed before the Session Manager returns control to you.

			Note that system commands beginning with a <big><b>)</b></big> cannot be executed through <big><b>{quad}LX</b></big>.

			==See Also==
			* [[System Command LOAD\|)LOAD]]
			* [[System Command SAVE\|)SAVE]]
			* [[System Command XLOAD\|)XLOAD]]

	{{System Variables}}		{{System Variables}}

Paul Robinson at 06:43, 23 February 2013

2013-02-23T06:43:32Z

← Older revision		Revision as of 02:43, 23 February 2013
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	Example usage:		Example usage:
	: {quad}LX{:=}'Start'		:<code> {quad}LX{:=}'Start'</code>

	When this workspace is saved, the next time it is loaded, it will attempt to start the function '''Start'''. An error will occur if the function named in {quad}LX is not present when the workspace is loaded.		When this workspace is saved, the next time it is loaded, it will attempt to start the function '''Start'''. An error will occur if the function named in {quad}LX is not present when the workspace is loaded.

Paul Robinson: new

2013-02-23T06:43:00Z

new

New page

<h1>{quad}LX - Latent Expression</h1>

The {quad}LX variable is used within a workspace to set the action to take when the workspace is loaded. Typically it is set to the name of a function in the workspace. {quad}LX defaults to null.

Example usage:
: {quad}LX{:=}'Start'

When this workspace is saved, the next time it is loaded, it will attempt to start the function '''Start'''. An error will occur if the function named in {quad}LX is not present when the workspace is loaded.

{{System Variables}}