System Variable ELX: Difference between revisions

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m (Quad DM, useful 'where')
 
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Note that <apll>⎕ELX</apll> can be localized and set dynamically to whatever it needs to deal with errors appropriately.<br>
Note that <apll>⎕ELX</apll> can be localized and set dynamically to whatever it needs to deal with errors appropriately.<br>
An APL Interpreter error (such as 'Domain Error') which '''triggers ⎕ELX''' will ''also'' send a Diagnostic Error Message to<br>
An APL Interpreter error (such as 'Domain Error') which '''triggers ⎕ELX''' will ''also'' send a Diagnostic Error Message to<br>
⎕DM, for debugging purposes, if needed by User.
⎕DM, for debugging purposes, if needed by User.  '''⎕ELX is useful''' in situations when a ''known error occurs'' and the User Function<br>
knows how to '''work around or deal with it appropriately''' by say branching to a special line of APL code.


'''See ALSO: [[System_Function_EA|⎕EA Execute Alternate]] and [[System_Variable_DM|Quad DM or ⎕DM]]'''
'''See ALSO: [[System_Function_EA|⎕EA Execute Alternate]] and [[System_Variable_DM|Quad DM or ⎕DM]]'''

Latest revision as of 18:11, 11 February 2015

⎕ELX - Error Latent Expression

⎕ELX Set action to take on error
⎕ELX←'string'

This system variable takes a string. That string is executed when the interpreter encounters an error. In particular the string may...

  • call a function
  • jump to a particular label

Note that ⎕ELX can be localized and set dynamically to whatever it needs to deal with errors appropriately.
An APL Interpreter error (such as 'Domain Error') which triggers ⎕ELX will also send a Diagnostic Error Message to
⎕DM, for debugging purposes, if needed by User. ⎕ELX is useful in situations when a known error occurs and the User Function
knows how to work around or deal with it appropriately by say branching to a special line of APL code.

See ALSO: ⎕EA Execute Alternate and Quad DM or ⎕DM


System Variables (A value may be assigned to these except for ⎕DM)
⎕ALX ⎕CT ⎕DM ⎕DT ⎕ELX ⎕FC ⎕FEATURE ⎕FPC ⎕IC ⎕IO
⎕LR ⎕LX ⎕PP ⎕PR ⎕PW ⎕RL ⎕SA ⎕WSID
Niladic System Functions (a value cannot be assigned to these)
⎕A ⎕AV ⎕EM ⎕ET ⎕LC ⎕NNAMES ⎕NNUMS ⎕SI ⎕SYSID ⎕SYSVER
⎕T ⎕TC ⎕TCBEL ⎕TCBS ⎕TCESC ⎕TCFF ⎕TCHT ⎕TCLF ⎕TCNL ⎕TCNUL
⎕TS ⎕WA
Monadic or dyadic system functions (a value cannot be assigned to these)
⎕AT ⎕CR ⎕DC ⎕DFT ⎕DL ⎕DR ⎕EA ⎕EC ⎕ERROR ⎕ES
⎕EX ⎕FMT ⎕FX ⎕MF ⎕NAPPEND ⎕NC ⎕NCREATE ⎕NERASE ⎕NINFO ⎕NL
⎕NLOCK ⎕NREAD ⎕NRENAME ⎕NREPLACE ⎕NRESIZE ⎕NSIZE ⎕NTIE ⎕NUNTIE ⎕STOP ⎕TF
⎕TRACE ⎕UCS ⎕VR
Note that quad functions and variables (except for the ⎕A family of functions) are case insensitive


See Also
System Commands System Variables and Functions Operators


Keyboard
Alt+Shift ⍪ ≡ ≢ ⍒ ⍋ ⌽ ⍉ ⊖ ⍟ ⍱ ⍲ ⍠ ⌹
Alt ⋄ ¨ ¯ < ≤ ∅ ≥ > ≠ ∨ ∧ × ÷
Shift ~ ! @ # $ % ^ & * ( ) _ +
Key ` 1 2 3 4 5 6 7 8 9 0 - =
Alt+Shift ⍷ √ ⍨ ⍸ ⍥ ⍣ ⍞ ⍬ ⊣
Alt ? ⍵ ∊ ⍴ § ↑ ↓ ⍳ ○ π ← → ⊢
Shift Q W E R T Y U I O P { } |
Key q w e r t y u i o p [ ] \
Alt+Shift ∫ ∂ ⌻ ⍢ ⍙ ⍤ ⍫ ⌷
Alt ⍺ ⌈ ⌊ ∞ ∇ ∆ ∘ ‼ ⎕ ⍎ ⍕
Shift A S D F G H J K L : "
Key a s d f g h j k l ; '
Alt+Shift ⊆ ⊇ χ ⍡ ⍭ ⊙
Alt ⊂ ⊃ ∩ ∪ ⊥ ⊤ ⍦ ⍝ ⍀ ⌿
Shift Z X C V B N M < > ?
Key z x c v b n m , . /
NARS 2000 Lang
Tool
Bar 		← → + - × ÷ * ⍟ ⌹ ○ ! ? √ | ⌈ ⌊ ⊥ ⊤ ⊣ ⊢
≡ ≢ < ≤ = ≥ > ≠ ∨ ∧ ⍱ ⍲ ↑ ↓ ⊂ ⊃ ⌷ ⍋ ⍒
⍳ ∊ ⍸ ⍷ ∪ ∩ ⊆ ⊇ ~ § π .. , ⍪ ⍴ ⌽ ⊖ ⍉
/ \ ⌿ ⍀ ⊙ ¨ ⍨ ⍤ ⍣ ⍡ ⍥ ⍦ . ∘ ⍠ ‼ ⌻ ∂ ∫ ⍞ ⎕ ⍎ ⍕
⋄ ⍝ ∇ ∆ ⍙ _ ⍺ ⍵ ¯ ⍬ ∞ ∅
Second Row i j k i j k l g p r v x

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