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InitializationValue

[Experimental]

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represents the settable persistent value with which the symbol sym will be initialized.

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InitializationValue["context`name"]

represents the settable initialization value for the symbol with the specified complete name.

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InitializationValue[sym,{loc1,…}]

specifies the persistence locations to search for a possible initialization value.

Details and Options

Examples

open allclose all

Basic Examples  (2)Summary of the most common use cases

Set a value to be evaluated every time the kernel starts:

In[1]:=1
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https://wolfram.com/xid/0dqvucvws2y-siknch
Out[1]=1

Set an initialization value for a variable:

In[1]:=1
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https://wolfram.com/xid/0dqvucvws2y-gcmmbn
Out[1]=1

Get any initialization value defined:

In[2]:=2
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https://wolfram.com/xid/0dqvucvws2y-e3lemv
Out[2]=2

Initialize the variable from the persistent value in the current kernel session:

In[3]:=3
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https://wolfram.com/xid/0dqvucvws2y-ehnzv9
Out[3]=3
In[4]:=4
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https://wolfram.com/xid/0dqvucvws2y-67eynj
In[5]:=5
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https://wolfram.com/xid/0dqvucvws2y-t67nui
Out[5]=5

Remove the initialization value:

In[6]:=6
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https://wolfram.com/xid/0dqvucvws2y-uesylc

Scope  (1)Survey of the scope of standard use cases

Set an initialization value in the default persistence location:

In[1]:=1
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https://wolfram.com/xid/0dqvucvws2y-onnj1q
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/0dqvucvws2y-2whx5z

Set an initialization value in the "KernelSession" persistence location:

In[3]:=3
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https://wolfram.com/xid/0dqvucvws2y-f7lg0c

The first value found in $PersistencePath is used:

In[4]:=4
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https://wolfram.com/xid/0dqvucvws2y-v0g1tw
Out[4]=4
In[5]:=5
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https://wolfram.com/xid/0dqvucvws2y-r3y0n0
Out[5]=5

Find all initialization values ever defined:

In[6]:=6
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https://wolfram.com/xid/0dqvucvws2y-n9syjj
Out[6]=6

Generalizations & Extensions  (1)Generalized and extended use cases

Set an initialization value for parallel subkernels:

In[1]:=1
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https://wolfram.com/xid/0dqvucvws2y-ylxt4z

All newly launched parallel subkernels use the given value:

In[2]:=2
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https://wolfram.com/xid/0dqvucvws2y-4g0a51
In[3]:=3
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https://wolfram.com/xid/0dqvucvws2y-touiop
Out[3]=3

Remove the initialization value:

In[4]:=4
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https://wolfram.com/xid/0dqvucvws2y-yyzzee

Options  (5)Common values & functionality for each option

EvaluationEnvironment  (1)

Set an initialization value for parallel subkernels:

In[1]:=1
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https://wolfram.com/xid/0dqvucvws2y-r8vudd

MergingFunction  (1)

Give a default value for a variable:

In[1]:=1
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https://wolfram.com/xid/0dqvucvws2y-121o5v

Set a custom merging function for initialization values of the variable:

In[2]:=2
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https://wolfram.com/xid/0dqvucvws2y-umbtzu
Out[2]=2
In[3]:=3
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https://wolfram.com/xid/0dqvucvws2y-0bwdsm

Specify initialization values at different persistence locations:

In[4]:=4
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https://wolfram.com/xid/0dqvucvws2y-yld5kp

The custom merging function is used to return the list of all values on $PersistencePath:

In[5]:=5
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https://wolfram.com/xid/0dqvucvws2y-imt46o
Out[5]=5

Use a different merging function for a particular value lookup:

In[6]:=6
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https://wolfram.com/xid/0dqvucvws2y-5q2vie
Out[6]=6

ValuePreprocessingFunction  (1)

Give a default value for an initialization value:

In[67]:=67
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https://wolfram.com/xid/0dqvucvws2y-qucy5n

Set a a custom value preprocessing function that accepts only integers:

In[68]:=68
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https://wolfram.com/xid/0dqvucvws2y-24izaz
In[69]:=69
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https://wolfram.com/xid/0dqvucvws2y-8mk16z
Out[69]=69
In[70]:=70
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https://wolfram.com/xid/0dqvucvws2y-5v61ks

Assign an integer at any persistence location:

In[71]:=71
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https://wolfram.com/xid/0dqvucvws2y-8h67b2

Assigning anything else generates an error, and the assignment is not performed:

In[72]:=72
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https://wolfram.com/xid/0dqvucvws2y-y88h52

PersistenceTime  (1)

Define an initialization that will expire in 5 seconds:

In[1]:=1
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https://wolfram.com/xid/0dqvucvws2y-5onlt0
In[2]:=2
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https://wolfram.com/xid/0dqvucvws2y-qxdech
Out[2]=2
In[3]:=3
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https://wolfram.com/xid/0dqvucvws2y-mu8iv6
Out[3]=3

ExpirationDate  (1)

Define an initialization value that expires at the beginning of next year:

In[1]:=1
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https://wolfram.com/xid/0dqvucvws2y-j07py1

Applications  (2)Sample problems that can be solved with this function

Override the default persistence base in all kernels started under the current front end session:

In[1]:=1
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https://wolfram.com/xid/0dqvucvws2y-i1dxhj

Quit and restart the kernel:

In[2]:=2
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https://wolfram.com/xid/0dqvucvws2y-crq4g9
In[3]:=3
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https://wolfram.com/xid/0dqvucvws2y-4vqztk
Out[3]=3

Set a value for $GeoLocation tied to your login account:

In[1]:=1
✖
https://wolfram.com/xid/0dqvucvws2y-xb4a07

Properties & Relations  (2)Properties of the function, and connections to other functions

Initialization values are stored in persistent objects:

In[1]:=1
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https://wolfram.com/xid/0dqvucvws2y-9soiuh
In[2]:=2
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https://wolfram.com/xid/0dqvucvws2y-nosrbc
Out[2]=2

List the existing initialization values in all editable persistence locations:

In[1]:=1
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https://wolfram.com/xid/0dqvucvws2y-wgtwqg
Out[1]=1

Remove them:

In[2]:=2
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https://wolfram.com/xid/0dqvucvws2y-jhwzrb

Possible Issues  (1)Common pitfalls and unexpected behavior

Create two initialization values for a symbol in different locations:

In[1]:=1
✖
https://wolfram.com/xid/0dqvucvws2y-dhsrmc

Remove by default removes only the value in the location given by $PersistenceBase:

In[2]:=2
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https://wolfram.com/xid/0dqvucvws2y-y8e29a
In[3]:=3
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https://wolfram.com/xid/0dqvucvws2y-jdbo4p
Out[3]=3

Remove all values that might exist anywhere in the locations given by $PersistencePath:

In[4]:=4
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https://wolfram.com/xid/0dqvucvws2y-6iica
In[5]:=5
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https://wolfram.com/xid/0dqvucvws2y-3dvr9p
Out[5]=5
Wolfram Research (2017), InitializationValue, Wolfram Language function, https://reference.wolfram.com/language/ref/InitializationValue.html (updated 2019).
✖
Wolfram Research (2017), InitializationValue, Wolfram Language function, https://reference.wolfram.com/language/ref/InitializationValue.html (updated 2019).

Text

Wolfram Research (2017), InitializationValue, Wolfram Language function, https://reference.wolfram.com/language/ref/InitializationValue.html (updated 2019).

✖
Wolfram Research (2017), InitializationValue, Wolfram Language function, https://reference.wolfram.com/language/ref/InitializationValue.html (updated 2019).

CMS

Wolfram Language. 2017. "InitializationValue." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2019. https://reference.wolfram.com/language/ref/InitializationValue.html.

✖
Wolfram Language. 2017. "InitializationValue." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2019. https://reference.wolfram.com/language/ref/InitializationValue.html.

APA

Wolfram Language. (2017). InitializationValue. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/InitializationValue.html

✖
Wolfram Language. (2017). InitializationValue. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/InitializationValue.html

BibTeX

@misc{reference.wolfram_2025_initializationvalue, author="Wolfram Research", title="{InitializationValue}", year="2019", howpublished="\url{https://reference.wolfram.com/language/ref/InitializationValue.html}", note=[Accessed: 22-June-2025 ]}

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@misc{reference.wolfram_2025_initializationvalue, author="Wolfram Research", title="{InitializationValue}", year="2019", howpublished="\url{https://reference.wolfram.com/language/ref/InitializationValue.html}", note=[Accessed: 22-June-2025 ]}

BibLaTeX

@online{reference.wolfram_2025_initializationvalue, organization={Wolfram Research}, title={InitializationValue}, year={2019}, url={https://reference.wolfram.com/language/ref/InitializationValue.html}, note=[Accessed: 22-June-2025 ]}

✖
@online{reference.wolfram_2025_initializationvalue, organization={Wolfram Research}, title={InitializationValue}, year={2019}, url={https://reference.wolfram.com/language/ref/InitializationValue.html}, note=[Accessed: 22-June-2025 ]}