caisin/typst
1
0
Fork 0
mirror of https://github.com/typst/typst synced 2025-05-16 18:15:29 +08:00
Code Issues Packages Projects Releases Wiki Activity

Rephrased 'read-only' as recommended by @MDLC01

Browse Source
This commit is contained in:
Ullrich Koethe 2025-03-04 21:04:44 +01:00 committed by GitHub
parent 262ec96a90
commit 7f9ddfbd80
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
1 changed files with 19 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
docs/reference/language/context.md
View File

@ -69,12 +69,12 @@ When a property is changed, the response to the query changes accordingly:
#context text.lang
```
The output of a `#context ...` call is _read-only_ in the form of opaque
`content`. Write access is prohibited, as it would often result in
invalid code: If the context changes between read and write, overwriting
a property would cause an inconsistent system state. In fact,
context-dependent property fields are read-only even within the context
itself:
The output of a `#context ...` call is static in the form of opaque
`content`. Write access to context output is prohibited, as it would
often result in invalid code: If the context changes between read and
write, overwriting a property would cause an inconsistent system state.
In fact, context-dependent property fields are immutable constants even
within the context itself:
```example
#set text(lang: "en")
@ -88,12 +88,13 @@ itself:
Both calls have the same output 'en', because `text.lang` is assigned
upon entry in the context and remains constant until the end of its scope
(the closing `]`). Compare this to the previous example: there we
got two different results because we created two different contexts.
(the closing `]`). It does not "see" the `#set text(lang: "fr")` before
call 2. Compare this to the previous example: there we got two different
results because we created two different contexts.
However, the read-only restriction only applies to the property fields
themselves. Content creation instructions _do_ see the effect of the
set rule. Consider the same example with font size:
However, immutability only applies to the property fields themselves.
Content creation instructions within a context _do_ see the effect of
the set rule. Consider the same example with font size:
```example
#set text(size: 50pt)
@ -105,13 +106,12 @@ set rule. Consider the same example with font size:
]
```
The second call still outputs '50pt', because `text.size` is a constant.
Call 2 still outputs '50pt', because `text.size` is a constant.
However, this output is printed in '25pt' font, as specified by the set
rule before the call. This illustrates the importance of picking the
rule before the call. This illustrates the importance of picking the
right insertion point for a context to get access to precisely the right
styles.
If you need access to updated property fields after a set rule, you can
use nested contexts:
styles. If you need access to updated property fields after a set rule,
you can use nested contexts:
```example
#set text(lang: "en")
@ -171,8 +171,9 @@ original size
```
but convenient alternatives like this do not exist for most properties.
For example, to double the spacing between the lines of an equation block,
you can use the same technique in a show rule. In this case, explicitly
This makes contexts a powerful and versatile concept. For example,
to double the spacing between the lines of an equation block, you can
use the same resizing technique in a show rule. In this case, explicitly
adding the `context` keyword is not necessary, because a show rule
establishes a context automatically: