publicVariable: Difference between revisions

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{{Command|= Comments
{{RV|type=command
____________________________________________________________________________________________


| ofp |= Game name
|game1= ofp
|version1= 1.34


|1.34|= Game version
|game2= ofpe
|version2= 1.00


|arg= local |= Arguments in MP
|game3= arma1
|version3= 1.00


|eff= global |= Effects in MP
|game4= arma2
____________________________________________________________________________________________
|version4= 1.00


| Broadcasts [[missionNamespace]] variable and its value to all computers. The data is sent consequently and reliably to all clients. Using [[publicVariable]] too frequently in a given period of time can cause other parts of the game to experience bandwidth problems.
|game5= arma2oa
|version5= 1.50


<br><br>Variables broadcast with [[publicVariable]] during a mission stay persistent for JIP (Join In Progress) clients. Such persistent variables are synced to the JIP client before the first batch of client side [[Event Scripts]] are ran.
|game6= tkoh
|version6= 1.00


<br><br>The following [[:Category:Types|Types]] of data are supported:<br>
|game7= arma3
* [[Number]]
|version7= 0.50
''Since OFP version 1.34'':
 
* [[Boolean]]
|gr1= Multiplayer
* [[Object]]
* [[Group]]
Since ArmA version 1.00:
* [[String]]
''Since ArmA version 1.09'':
* [[Array]]
* [[Code]]
''Since Arma 3 version 1.26'':
* [[Nothing]] ([[nil]])
<br>
''Limitations'': Cannot use reserved names, such as "[[player]]" or "[[west]]" or "[[side]]", etc. It is also not possible to transfer references to entities which are local, like [[Script|scripts]], [[Display|displays]], or local objects. [[Team Member]] is also not supported.


|= Description
|gr2= Variables
____________________________________________________________________________________________


| '''publicVariable''' varName |= Syntax
|arg= local


|p1= varName: [[String]] |= Parameter 1
|eff= global


| [[Nothing]] |= Return value
|descr= Reliably broadcasts [[missionNamespace]] variable and its '''current''' value to all computers (server/client).<br>
____________________________________________________________________________________________
Variables broadcast with [[publicVariable]] during a mission will be available to [[Multiplayer Scripting#Join In Progress|JIP]] clients with the value they held at the time.<br>
 
Such variables are persistent and sent to the JIP client before the first batch of client-side [[Event Scripts]] (such as [[init.sqf]]) is run.
|x1= <code>[[publicVariable]] "CTFscoreOne";</code> |= Example 1
{{Feature|important|Using [[publicVariable]] too frequently and/or with a lot of data can cause other aspects of the game to experience bandwidth problems.}}
|x2= <code>myPubVar = [123, "456", [[true]]];
<br>
[[publicVariable]] "myPubVar";</code> |= Example 2
The following [[:Category: Data Types| Data Types]] are supported:
____________________________________________________________________________________________
{{{!}} class="wikitable align-center"
! Type
{{!}} [[Number]]
{{!}} [[Boolean]]
{{!}} [[Object]]
{{!}} [[Group]]
{{!}} [[String]]
{{!}} [[Structured Text|Text]]
{{!}} [[Array]]
{{!}} [[Code]]
{{!}} [[Nothing]] ([[nil]])
{{!}} [[HashMap]]
{{!}}-
! Since
{{!}} colspan="4" {{!}} {{GVI|ofp|1.34}}
{{!}} colspan="2" {{!}} {{GVI|arma1|1.00}}
{{!}} colspan="2" {{!}} {{GVI|arma1|1.09}}
{{!}} {{GVI|arma3|1.26}}
{{!}} {{GVI|arma3|2.02}}
{{!}}}


| [[6thSense.eu:EG|MP editing guide]], [[addPublicVariableEventHandler]], [[publicVariableClient]], [[publicVariableServer]] |= See also
{{Feature|important|
| |=
It is not possible (and illogical) to transfer a local entity reference, such as [[Script Handle|scripts]], [[Display|displays]] or [[createVehicleLocal|local objects]].<br>
Also, note that [[Team Member]] is not supported.
}}
}}


<h3 style="display:none">Notes</h3>
|s1= [[publicVariable]] varName
<dl class="command_description">
<!-- Note Section BEGIN -->
 
<dd class="notedate">Posted on 3 Aug, 2006 23:03
<dt class="note">[[User:Hoz|Hoz]]<dd class="note">
<dd class="note">This command broadcasts a variable to all clients, but as soon as you change the variable again, you have to use '''publicVariable''' again, as it does not automatically synchronise it.
 
<dd class="notedate">Posted on 12 April, 2008
<dt class="note">[[User:Icemotoboy|Icemotoboy]]<dd class="note">
Be sure to place your variable name in quotation marks.  This may sound awfully simple, but many times I have forgotten to do this, and it has resulted in no end of headaches for me.


<dd class="notedate">Posted on 2 Feb, 2008
|p1= varName: [[String]] - the [[Variables#Global Scope|global variable]]'s [[Identifier]]
<dt class="note">[[User:Dr_Eyeball|Dr_Eyeball]]<dd class="note">
When initialising a public variable to handle '''JIP''', you will usually first want to check if the public variable has already been (broadcast, received and) set locally. Otherwise you may inadvertantly overwrite the broadcast value with your default value.<br>
<br>
To perform this check, use code similar to the following to first check that the variable is nil:
if ([[isNil]] "PV_abc") then
{
  // set the nil variable with a default value for server and both JIP & 'join at mission start'
  PV_abc = [7, 8, 9];
};
// else public variable has already been set due to a public variable broadcast.
<br>


<dd class="notedate">Posted on 14 July, 2011
|r1= [[Nothing]]
<dt class="note">[[User:kju|kju]]<dd class="note">
To make Dr_Eyeball's note even more clear:
For JIP players pV'ed variables are received and set '''BEFORE''' the init.sqf.
So to avoid the received variables getting overwritten by variable initialization normally done in the init.sqf, you '''HAVE TO''' to use the 'if ([[isNil]] "PV_abc")' pattern.
It says literally: "Only initialize value it has not yet been set. And in a JIP this may already been the cause due to publicVariable use".


<dd class="notedate">Posted on 21 September, 2013
|x1= <sqf>
<dt class="note">[[User:Killzone_Kid|Killzone_Kid]]<dd class="note">
TAG_MyPublicVariable = 0;
To make Dr_Eyeball's and kju's notes even more clear, public variable is persistent. Once it has been broadcast it will be delivered to all clients, present and future. Therefore it is wise to check if the variable already exists on a client due to it being persistent before initialising its value.
TAG_MyPublicVariable = 1;
publicVariable "TAG_MyPublicVariable"; // other clients will receive the "TAG_MyPublicVariable" variable with a 1 value


<dd class="notedate">Posted on 23 February, 2014
TAG_MyPublicVariable = 2; // needs to be broadcast again - synchronisation is not automatic
<dt class="note">[[User:MulleDK13|=MulleDK13]]<dd class="note">
</sqf>
Just to clarify, when players JIP, they get the value of the variable from the last call to publicVariable, not the current value of the variable. Eg. with
<code>SomeVar = 5; [[publicVariable]] "SomeVar"; SomeVar = 10;</code>
Connecting players will receive 5, not the current value of 10.


<!-- Note Section END -->
|x2= JIP example:
</dl>
<sqf>
if (isNil "TAG_CurrentTarget") then // has the variable already been set and broadcast?
{
TAG_CurrentTarget = objNull; // if not, set it on the local machine
};


<h3 style="display:none">Bottom Section</h3>
player doTarget TAG_CurrentTarget;
[[Category:Scripting Commands|PUBLICVARIABLE]]
</sqf>
[[Category:Scripting Commands OFP 1.99|{{uc:{{PAGENAME}}}}]]
[[Category:Scripting Commands OFP 1.96|PUBLICVARIABLE]]
[[Category:Scripting Commands OFP 1.46|PUBLICVARIABLE]]
[[Category:Scripting Commands ArmA|PUBLICVARIABLE]]
[[Category:Command_Group:_Multiplayer|{{uc:{{PAGENAME}}}}]]
[[Category:Scripting Commands ArmA2|{{uc:{{PAGENAME}}}}]]
[[Category:Scripting Commands Arma 3|{{uc:{{PAGENAME}}}}]]
[[Category:Scripting_Commands_Take_On_Helicopters|{{uc:{{PAGENAME}}}}]]


<!-- CONTINUE Notes -->
|x3= <sqf>
<dl class="command_description">
TAG_BossName = "EvilBigBoss";
<dd class="notedate">Posted on October 19, 2014 - 00:21 (UTC)</dd>
<dt class="note">[[User:DreadedEntity|DreadedEntity]]</dt>
<dd class="note">
I'm pretty far down the notes list so I hope this doesn't get buried.<br><br>


For clarity, after a variable has been publicVariable'd, scripts in all clients can use it as if it had been defined locally.<br>
publicVariable TAG_BossName; // wrong - will try to publicVariable "EvilBigBoss" variable, that does not exist
publicVariable "TAG_BossName"; // correct - important, do not forget the QUOTES
</sqf>


Variables that have been publicVariable'd do not need to be pre-defined on receiving clients. In fact, this could cause issues with JIP players overwriting a publicVariable value, as mentioned above. '''(tested in A3 1.32.127785)'''<br>
|seealso= [[Multiplayer Scripting]] [[Initialisation Order]] [[addPublicVariableEventHandler]] [[publicVariableClient]] [[publicVariableServer]] [[Variables#Global Scope|Global Variable]] [[Event Scripts]] [[Multiplayer Scripting#Join In Progress|Join In Progress]]
Local variables cannot be publicVariable'd. '''(tested in A3 1.32.127785)''' (tested by having dedicated server publicVariable a local variable, then trying to hint it on client. Error was "Undefined variable in expression")
}}
</dd>
</dl>
<!-- DISCONTINUE Notes -->

Latest revision as of 15:57, 26 July 2023

Logo A0.png1.34ofpe logo.png1.00Logo A1 black.png1.00Logo A2.png1.00A2 OA Logo.png1.50tkoh logo small.png1.00Arma 3 logo black.png0.50
LALocalGEGlobal
Hover & click on the images for description

Description

Description:
Reliably broadcasts missionNamespace variable and its current value to all computers (server/client).
Variables broadcast with publicVariable during a mission will be available to JIP clients with the value they held at the time.
Such variables are persistent and sent to the JIP client before the first batch of client-side Event Scripts (such as init.sqf) is run.
⚠
Using publicVariable too frequently and/or with a lot of data can cause other aspects of the game to experience bandwidth problems.


The following Data Types are supported:

Type Number Boolean Object Group String Text Array Code Nothing (nil) HashMap
Since Logo A0.png1.34 Logo A1 black.png1.00 Logo A1 black.png1.09 Arma 3 logo black.png1.26 Arma 3 logo black.png2.02
⚠
It is not possible (and illogical) to transfer a local entity reference, such as scripts, displays or local objects.
Also, note that Team Member is not supported.
Groups:
MultiplayerVariables

Syntax

Syntax:
publicVariable varName
Parameters:
varName: String - the global variable's Identifier
Return Value:
Nothing

Examples

Example 1:
TAG_MyPublicVariable = 0; TAG_MyPublicVariable = 1; publicVariable "TAG_MyPublicVariable"; // other clients will receive the "TAG_MyPublicVariable" variable with a 1 value TAG_MyPublicVariable = 2; // needs to be broadcast again - synchronisation is not automatic
Example 2:
JIP example:
if (isNil "TAG_CurrentTarget") then // has the variable already been set and broadcast? { TAG_CurrentTarget = objNull; // if not, set it on the local machine }; player doTarget TAG_CurrentTarget;
Example 3:
TAG_BossName = "EvilBigBoss"; publicVariable TAG_BossName; // wrong - will try to publicVariable "EvilBigBoss" variable, that does not exist publicVariable "TAG_BossName"; // correct - important, do not forget the QUOTES

Additional Information

See also:
Multiplayer Scripting Initialisation Order addPublicVariableEventHandler publicVariableClient publicVariableServer Global Variable Event Scripts Join In Progress

Notes

Report bugs on the Feedback Tracker and/or discuss them on the Arma Discord or on the Forums.
Only post proven facts here! Add Note
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