Symbolic path: Difference between revisions

Latest revision as of 10:25, 24 October 2024

A symbolic path (aka. pseudo path) is a placeholder that represents one or more well-known locations in LabVIEW. When specifying a path to a file or folder inside a well-known location, rather than specifying the absolute path, the path is specified relative to the symbolic path. When accessing the path, it is resolved to the actual location, which may be different between machines, platforms, targets, and versions of LabVIEW.

A VI that uses "<vilib>:\a.vi" may resolve to "<labview>\vi.lib\a.vi" when loaded for a desktop target, and "<labview>\vi.lib\fpga\a.vi" when loaded for a FPGA target.

A symbolic path can also refer to multiple locations that overlay each other as if they were a single directory. If a file with the same name exists in multiple directories, the first file found is used. The order in which directories are scanned may vary and can be determined using the Build And Resolve Symbolic Path VI with "symbolic path id" set to "<libdir>".

Syntax

Symbolic paths are used similar to drive letters in Windows. For example, "<userlib>:\myfile.txt" specifies a file named myfile.txt in the user.lib directory.

Usage

LabVIEW uses symbolic paths internally to store paths to files and folders. For example, the lvproj file format stores paths to files using symbolic paths. Symbolic paths are also useful for VI Scripting.

Resolving symbolic paths

In order to access the actual path that a symbolic path represents, it must be resolved. In LabVIEW 2023 Q3 and later, the Build And Resolve Symbolic Path VI should be used. In earlier versions from LabVIEW 2015 and later, the Resolve Symbolic Path VI should be used. For even earlier versions, the private Resolve Symbolic Path method, which is deprecated since LabVIEW 8.5, can be used.

External links

Resolving Symbolic Paths (LAVA)
Resolution of Pseudopaths per Target (NI forums)

@@ Line 1: / Line 1: @@
-When files are located beneath certain special folders, callers that link to these files will link to them using a ''pseudopath'', rather than an absolute or relative path.  The ''pseudopath'' will be relative to the special folder.  The following table lists these special folders and their ''pseudopath'':
+A '''symbolic path''' (aka. ''pseudo path'') is a placeholder that represents one or more well-known locations in [[LabVIEW]]. When specifying a [[path]] to a file or folder inside a well-known location, rather than specifying the absolute path, the path is specified relative to the symbolic path. When accessing the path, it is resolved to the actual location, which may be different between machines, platforms, targets, and versions of LabVIEW.
-{| class="wikitable"
+A [[VI]] that uses "<vilib>:\a.vi" may resolve to "<labview>\vi.lib\a.vi" when loaded for a desktop target, and "<labview>\vi.lib\fpga\a.vi" when loaded for a [[FPGA]] target.
-|-
-! pseudopath
-! description
-! actual path
-|-
-| <userlib>
-| User Libraries
-| <LabVIEW>\user.lib
-|-
-| <vilib>
-| NI Libraries and Addons
-| <LabVIEW>\vi.lib
-|-
-| <instrlib>
-| Instrument Drivers
-| <LabVIEW>\instr.lib
-|-
-| <help>
-| Help Files
-| <LabVIEW>\help
-|-
-| <menu>
-| Palette Menus
-| <LabVIEW>\menus
-|}
-Note that some of these can have the actual path changed by changing the settings in '''Tools>>Options'''. The whole point of the pseudopath is to indicate "load from whatever location this path is currently defined to be."
+A symbolic path can also refer to multiple locations that [[wikipedia:superimpose|overlay]] each other as if they were a single directory. If a file with the same name exists in multiple directories, the first file found is used. The order in which directories are scanned may vary and can be determined using the [[Build And Resolve Symbolic Path]] VI with "symbolic path id" set to "<libdir>".
-For example, if you have a VI located in the following location:
+==Syntax==
+Symbolic paths are used similar to drive letters in Windows. For example, "<userlib>:\myfile.txt" specifies a file named ''myfile.txt'' in the [[user.lib]] directory.
-<LabVIEW>\user.lib\_OpenG.lib\array\array.llb\Conditional Auto-Indexing Tunnel__ogtk.vi
+==Usage==
+LabVIEW uses symbolic paths internally to store paths to files and folders. For example, the [[lvproj]] file format stores paths to files using symbolic paths. Symbolic paths are also useful for [[VI Scripting]].
-Callers will link to this VI using the following ''pseudopath'':
+==Resolving symbolic paths==
+In order to access the actual path that a symbolic path represents, it must be resolved. In [[LabVIEW 2023 Q3]] and later, the [[Build And Resolve Symbolic Path]] VI should be used. In earlier versions from [[LabVIEW 2015]] and later, the [[Resolve Symbolic Path (VI)|Resolve Symbolic Path]] VI should be used. For even earlier versions, the private [[Resolve Symbolic Path (method)|Resolve Symbolic Path]] method, which is deprecated since [[LabVIEW 8.5]], can be used.
-<userlib>\_OpenG.lib\array\array.llb\Conditional Auto-Indexing Tunnel__ogtk.vi
+==See also==
+*[[List of symbolic paths]]
-''pseudopath'' are not generally encountered.  They are used mostly under the hood of LabVIEW, for example, when using the Application '''Linker:Read Info From File''' and '''Linker:Write Info To File''' methods.
+==External links==
+*[https://lavag.org/topic/10549-resolving-symbolic-paths/ Resolving Symbolic Paths] (LAVA)
+*[https://forums.ni.com/t5/Community-Documents/Resolution-of-Pseudopaths-in-LabVIEW-Per-Target-Invocation-of/ta-p/4087124 Resolution of Pseudopaths per Target] (NI forums)
-== When Using Modules (FPGA, RT, etc) ==
+[[Category:Development Environment]]
-A pseudopath may resolve to different actual files on disk depending upon which target the VI is loaded into. So a VI that is written to use <vilib>\a.vi may use <labview>\vi.lib\a.vi when loaded for the desktop target, but may use <labview>\vi.lib\fpga\a.vi when loaded for the FPGA target.