System Function EC: Difference between revisions

From NARS2000
Jump to navigationJump to search
VisualWikitext
(created quad EC page)
 
No edit summary
 
Line 1: Line 1:
<h1>{quad}EC - Execute Controlled</h1>
<h1>{quad}EC - Execute Controlled</h1>
{{BoxStart|⎕EC
{{BoxStart|<apll>⎕EC</apll>
| Execute Controlled "for a string expression"}}
| Execute Controlled "for a string expression"}}
{{BoxEnd|Z ← ⎕EC R &nbsp; <i>where argument R is a string expression and returned '''Z''' is a 3-element [mixed, nested] vector.</i>}}
{{BoxEnd|<apll>Z←⎕EC R</apll> &nbsp; where argument <apll>R</apll> is a string expression and returned <apll>Z</apll> is a 3-element [mixed, nested] vector.}}


==Monadic Function==
==Monadic Function==
Line 14: Line 14:
       <td></td>
       <td></td>
       <td></td>
       <td></td>
       <td>"R" is executed, and the result Z is a 3-item returned vector.</td>
       <td><apll>R</apll> is executed, and the result <apll>Z</apll> is a 3-item vector.</td>
     </tr>
     </tr>
     </table>
     </table>
Line 20: Line 20:
</tr>
</tr>
<tr>
<tr>
   <td>R should be a string expression. ⎕EC is frequently used for testing and debugging purposes.</td>
   <td><apll>R</apll> should be a string expression. <apll>⎕EC</apll> is frequently used for testing and debugging purposes.</td>
</tr>
</tr>


</table>
</table>
<br />
<br />
Return codes for Z: Normally, the '''first element''' of the return code (in variable '''Z''') represents an integer in the range 0 to 5, where:<br>
Return codes for <apll>Z</apll>: Normally, the first element of the return code (in variable <apll>Z</apll>) represents an integer in the range 0 to 5, where:<br>
0 = Error<br>
0 = Error<br>
1 = Expression with a result which would display (for debugging purposes this means '''OK''', '''R''' was '''not''' problematic.<br>
1 = Expression with a result which would display (for debugging purposes this means '''OK''', <apll>R</apll> was '''not''' problematic.<br>
2 = Expression with a result which would not display<br>
2 = Expression with a result which would not display<br>
3 = Expression with no explicit result<br>
3 = Expression with no explicit result<br>
4 = Branch to a line<br>
4 = Branch to a line<br>
5 = Simple goto / branch<br><br>
5 = Niladic goto / branch<br><br>
The second item in Z (returned) is the value that would be returned by ⎕ET (quad event type, without altering the current value of ⎕ET). The third item returned is the actual result ('''IF''' one is generated); for return code 3 or 5 the third item is 0 0⍴0; for return code 4 the third item is the argument to the branch; for return code 0 the third item is ⎕EM.
The second item in <apll>Z</apll> (returned) is the value that would be returned by <apll>⎕ET</apll> (quad event type, without altering the current value of <apll>⎕ET</apll>). The third item returned is the actual result ('''IF''' one is generated); for return code 3 or 5 the third item is <apll>0 0⍴0</apll>; for return code 4 the third item is the argument to the branch; for return code 0 the third item is <apll>⎕EM</apll>.
<br><br>
<br><br>


'''Quad Execute Controlled ⎕EC''' sample ''monadic'' calls:
'''Quad Execute Controlled <apll>⎕EC</apll>''' sample ''monadic'' calls:
<pre>
<pre>
       Z←⎕EC 'a÷1'  ⍝ Right argument FAILS(a÷1, because variable "a" does NOT exist).
       Z←⎕EC 'a÷1'  ⍝ Right argument FAILS(a÷1, because variable "a" does NOT exist).
Line 75: Line 75:


<br><br>
<br><br>
See also: '''[[System_Function_EA|⎕EA]]'''<br><br>
See also: [[System_Function_EA|<apll>⎕EA</apll>]]<br><br>


{{System Variables}}
{{System Variables}}
{{Article footer}}
{{Article footer}}

Latest revision as of 19:15, 12 December 2017

⎕EC - Execute Controlled

⎕EC Execute Controlled "for a string expression"
Z←⎕EC R   where argument R is a string expression and returned Z is a 3-element [mixed, nested] vector.

Monadic Function

Z←⎕EC R R is executed, and the result Z is a 3-item vector.
R should be a string expression. ⎕EC is frequently used for testing and debugging purposes.


Return codes for Z: Normally, the first element of the return code (in variable Z) represents an integer in the range 0 to 5, where:
0 = Error
1 = Expression with a result which would display (for debugging purposes this means OK, R was not problematic.
2 = Expression with a result which would not display
3 = Expression with no explicit result
4 = Branch to a line
5 = Niladic goto / branch

The second item in Z (returned) is the value that would be returned by ⎕ET (quad event type, without altering the current value of ⎕ET). The third item returned is the actual result (IF one is generated); for return code 3 or 5 the third item is 0 0⍴0; for return code 4 the third item is the argument to the branch; for return code 0 the third item is ⎕EM.

Quad Execute Controlled ⎕EC sample monadic calls: 

      Z←⎕EC 'a÷1'   ⍝ Right argument FAILS(a÷1, because variable "a" does NOT exist).
      ⍴Z
3                   ⍝ Thus a standard 3-element vector has been returned in Z
      Z             ⍝ Let's see what Z looks like:
 0  0 0  VALUE ERROR 
         ⍎     a÷1   
               ∧     
      Z[1]     ⍝ first element in Z is the return code, a zero was generated in this case, indicating an error, as listed above.
0
      Z[2]
 0 0
      Z[3]     ⍝ third element returned in Z is the actual nested string error message.
 VALUE ERROR 
 ⍎     a÷1   
       ∧  
 
      ⍝ A different test with "no problems" example:
      Z←⎕EC '6÷0.5' ⍝ RIGHT argument SUCCEEDS(6÷0.5) because 6 can be divided by 0.5; under normal circumstances the answer would be 12.
      ⍴Z
3
      Z
 1  0 0  12
      Z[1]       ⍝ first element in Z is the return code, a one was generated in this case, indicating no problem, as per the list above.
1                ⍝ again, 1 = success, no problems encountered
      Z[2]
 0 0
      Z[3]
12              ⍝ And Z[3] correctly holds the expected answer.

The Execute Controlled system function normally takes a string as its right argument. In particular the left argument string may normally:

  • call a function
  • jump to a particular label
  • perform ANY allowed APL operation (e.g. addition, multiplication, division, subtraction, floor, ceiling, logic test, etc...)
  • assign/set a value



See also: ⎕EA

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

[[Category:Mouse Group {{{1}}}|{{{2}}}]]

Retrieved from "https://wiki.nars2000.org/index.php?title=System_Function_EC&oldid=3141"