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ER: parsing of try ... catch ... #1608

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pkoppstein opened this issue Feb 28, 2018 · 3 comments
Open

ER: parsing of try ... catch ... #1608

pkoppstein opened this issue Feb 28, 2018 · 3 comments
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feature request

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@pkoppstein
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Some users are surprised by the failure of expressions such as:

jq 'try .data |= fromjson catch "STRING"'

Here, parentheses are required around the "TRY" clause. That's a bit surprising since jq is so good about using keywords in the case of if ... then ... else ... end, and perhaps also because |= is just a binary operator.
@nicowilliams
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I've been annoyed by this too. I think an end keyword would have made it easier for bison to disambiguate.

@nicowilliams
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I'm partial to obsoleting try ... catch ... and replacing it with try(exp; handler) as a special builtin function.

nicowilliams added a commit to nicowilliams/jq that referenced this issue Dec 29, 2019
@nicowilliams
Add try-catch-finally and fix jqlang#1608
cbe4b81 
We can't really fix the issues with try-catch syntax, but we can
introduce `try` as a function-like syntax, using `try(exp; handler)`
in preference to `(try exp catch (handler))`.

While we're at it, we can use the new `UNWINDING` opcode to implement
try-catch-finally as `try(exp; handler; finally)`.
@nicowilliams
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nicowilliams commented Dec 29, 2019 •
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I've got a commit cbe4b81 that introduces try(exp; handler) and try(exp; handler; finally) syntax, leaves the old try exp catch handler syntax, and changes the manual to a) use the new syntax, b) indicate that the old syntax is obsolete and may be removed.

As for try(exp), as it happens that was already legal because try exp was legal.

@nicowilliams nicowilliams mentioned this issue Dec 29, 2019
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nicowilliams added a commit to nicowilliams/jq that referenced this issue Dec 30, 2019
@nicowilliams
Add try-catch-finally and fix jqlang#1608
e8c874b 
We can't really fix the issues with try-catch syntax, but we can
introduce `try` as a function-like syntax, using `try(exp; handler)`
in preference to `(try exp catch (handler))`.

While we're at it, we can use the new `UNWINDING` opcode to implement
try-catch-finally as `try(exp; handler; finally)`.
nicowilliams added a commit that referenced this issue Jan 2, 2020
@nicowilliams
Add try-catch-finally and fix #1608
dd444a1 
We can't really fix the issues with try-catch syntax, but we can
introduce `try` as a function-like syntax, using `try(exp; handler)`
in preference to `(try exp catch (handler))`.

While we're at it, we can use the new `UNWINDING` opcode to implement
try-catch-finally as `try(exp; handler; finally)`.
nicowilliams added a commit to nicowilliams/jq that referenced this issue Jan 3, 2020
@nicowilliams
Add try-catch-finally and fix jqlang#1608
300f85b 
We can't really fix the issues with try-catch syntax, but we can
introduce `try` as a function-like syntax, using `try(exp; handler)`
in preference to `(try exp catch (handler))`.

While we're at it, we can use the new `UNWINDING` opcode to implement
try-catch-finally as `try(exp; handler; finally)`.
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@pkoppstein @itchyny @nicowilliams