Value.get: Accept "default" parameter#2010
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pfalcon wants to merge 1 commit into
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The idea is similar to e.g. Python's dict.get() method, which can take an
optional default if a given key doesn't exist in the dict.
This change would allow to users to "bootstrap" otherwise circular
dependencies in simple cases. For example, it allows to turn this
code:
```
from shiny.express import input, render, ui
@render.express
def myrender():
ui.input_select("sel", None, ["All", "So", "Much"], selected="All")
input.sel()
```
which doesn't render anything nor produces errors (underneath it throws
SilentException which isn't reported) into following code:
```
from shiny.express import input, render, ui
@render.express
def myrender():
ui.input_select("sel", None, ["All", "So", "Much"], selected=input.sel.get("All"))
input.sel.get("All")
```
which works as expected (initial selected value is "All", and if user
chooses another, it's preserved across myrender() run).
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The idea is similar to e.g. Python's dict.get() method, which can take an optional default if a given key doesn't exist in the dict.
This change would allow to users to "bootstrap" otherwise circular dependencies in simple cases. For example, it allows to turn this code:
which doesn't render anything nor produces errors (underneath it throws SilentException which isn't reported) into following code:
which works as expected (initial selected value is "All", and if user chooses another, it's preserved across myrender() run).