System Function ES
From NARS2000
Quad ES - Event Simulate - ⎕ES System Function
Event Simulate [with either Error Message(⎕EM) or Event Type(⎕ET)] - for debugging, user alerts, detailed at-length error messaging purposes.
Monadic Function
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| R may frequently be one of three distinct Cases: 1) Simple character scalar or vector; 2) Simple two-item vector of integers, 'normally' between -32767 and 32767; or 3) An empty vector. | ||||
| ⎕ES does not have a Z type return argument. It's effect on the APL interpreter is to show on the user's display, certain debugging information, depending on how the call to ⎕ES was made. |
Quad ES ⎕ES Event Simulate - sample monadic use/user session(with comments using ⍝ symbol):
⎕VR 'ErrorSim' ⍝Virtual representation of user-function ErrorSim. It has one right argument, A.
∇ ErrorSim A
[1] ⍝Simulate an error. If the test (next line, just below) inside the parentheses evaluate to True then Event IS simulated.
[2] ⎕ES(0=A)/'ZERO INVALID' ⍝Event Simulate occurs here, if A=0 then a user/SysOp error message will appear(in System Variable ⎕EM).
[3] '⎕ET(Event Type) = ',⎕ET ⍝ ⎕ES frequently affects sys var quad Event Type ⎕ET, although not presently in NARS.
[4] '⍴⎕EM(Error Message) = ',(⍴⎕EM),' ⎕EM:' ⍝ ⎕EM IS affected in NARS - IF the Error Condition evaluate to True(1).
[5] ⎕EM
∇ 2015 2 20 22 31 5 647 (UTC)
ErrorSim 45 ⍝ <<< In this event simulation(user types in ErrorSim 45), there should be NO EFFECT since 45 is not equal to 0.
⎕ET(Event Type) = 0 0 ⍝ As mentioned ⎕ET remains unaffected = {0 0}
⍴⎕EM(Error Message) = 3 0 ⎕EM: ⍝ Since there was NO error(no event simulation) ⎕EM is also unaffected - it has 3 empty rows(0 cols).
ErrorSim 0 ⍝ <<< In this event simulation(user types in ErrorSim 0); there SHOULD BE an EFFECT; A = 0 (test evaluates to True).
ZERO INVALID ⍝ Sure enough, the Error Message ⎕EM is returned by NARS/APL with ⎕EM = 'ZERO INVALID'
ErrorSim 0 ⍝ Normally APL would also return the user-function line number which 'failed' here ⎕ES returns zero.
∧
⎕EM ⍝ Sure enough, ⎕EM when typed in by user, shows the most recent simulated error message from ⎕ES.
ZERO INVALID
ErrorSim 0
∧
⎕ET ⍝ Also note that ⎕ET was not affected even though in some APL implementations ⎕ES can/will affect ⎕ET.
0 0
When is ⎕ES useful?
- You want to specifically get the user's attention when a certain error, input error, or other frequent error condition can/could occur.
- You want to show a More Detailed Error Message when a known error occurs.
- You are debugging a certain area of APL user-function code and want to test simulating the error condition(s).
- Since program/code suspension occurs at the CALLING POINT, not within the defined operation/user function per se, it translates to more focus on the input or arguments which may have caused/triggered the event to occur.
- It can be used, for example, to generate various return codes on system resource limitations encountered, see ⎕ET.
Dyadic Function
Not Currently Documented - Although Dyadic Event Simulate ⎕ES Use is implemented in some APL versions.
Note: ⎕ES is available as both a monadic and dyadic form system function, you cannot assign a value to it.
| 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 | ||||||||||||||||
