Vocabulary/assertdot
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assert. Assertion Control
Valid only inside an explicit definition.
Signals assertion failure if followed by a noun which is neither Boolean (1) nor an array: (1 1 1 ...) of all 1's.
Behaves as a no-op if followed by a noun which is either Boolean (1) or an array: (1 1 1 ...) of all 1's.
Common Uses
1. Check that the argument y is Boolean, else signal an error
assert. y e. 0 1
2. Write a test-script for an addon.
NB. Test script for selected J phrases. NB. The assertions must appear inside an explicit definition NB. in this case an anonymous one. 3 : 0'' assert. (3j5) -: 3 j. 5 assert. (3j5 3j6) -: 3 j. 5 6 assert. (3j5 4j5) -: 3 4 j. 5 assert. 1 -: 2 assert. (3j5 4j6) -: 3 4 j. 5 6 )
The script will stop loading with an assertion failure at the first line for which the assertion (Boolean test-phrase) is not obeyed.
load '~temp/122.ijs' |assertion failure: script | 1 -:2
Details
Note that assert. is followed by a single sentence and is not paired with end. .
More Information
Use the Foreign (9!:35) to disable all assert.-statements. Once disabled, the noun phrase following assert. is never evaluated.
Use the Foreign (9!:34) to discover if assert. is enabled.
trial=: 4 : 0 echo x ; 'trial: ON?' ; ((9!:34)'') ; ' y=' ; y assert. y ) (9!:35) 0 NB. switch asserts OFF 0 trial 1 ┌─┬──────────┬─┬───┬─┐ │0│trial: ON?│0│ y=│1│ └─┴──────────┴─┴───┴─┘ 1 trial 0 ┌─┬──────────┬─┬───┬─┐ │1│trial: ON?│0│ y=│0│ └─┴──────────┴─┴───┴─┘ (9!:35) 1 NB. switch asserts back ON 2 trial 1 ┌─┬──────────┬─┬───┬─┐ │2│trial: ON?│1│ y=│1│ └─┴──────────┴─┴───┴─┘ 3 trial 0 ┌─┬──────────┬─┬───┬─┐ │3│trial: ON?│1│ y=│0│ └─┴──────────┴─┴───┴─┘ |assertion failure: trial | y