System Variable DM: Difference between revisions

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<h1>{quad}DM - Diagnostic Message</h1>
<h1><aplxx>⎕DM</aplxx> - Diagnostic Message</h1>
{{BoxStart|⎕DM
{{BoxStart|⎕DM
| '''Diagnostic Message set to last error message string APL's Interpreter encountered'''.}}
| Diagnostic Message set to last error message the APL interpreter encountered.}}
{{BoxEnd|⎕DM <u>cannot be assigned a value by the User.</u> '''APL interpreter sets its string value''' when it encounters an error, e.g. 'DOMAIN ERROR'.}}
{{BoxEnd|Unlike other system variables, <apll>⎕DM</apll> cannot be assigned a value by the User.  The APL interpreter sets its value when it encounters an error, e.g. <apll>DOMAIN ERROR</apll>.}}


⎕DM is set by APL to the last diagnostic error message the Interpreter encountered.<br>
It is for informational, for diagnostic purposes only.  User cannot set its value.<br>
'''⎕DM is useful''' for <u>'''viewing'''</u> the last error message, particularly if Error Trapping is<br>
being used, or for system-function and user-function '''debugging purposes'''.  Just type in:


: ⎕DM
<apll>⎕DM</apll> is set by APL to the last diagnostic error message the Interpreter encountered.  It is for informational and diagnostic purposes only.  User cannot set its value.


<apll>⎕DM</apll> is useful for viewing the last error message, particularly if Error Trapping is being used, or for system-function and user-function debugging purposes.  For example:


: ⍴⎕DM  ⍝In a CLEAR APL Workspace ⎕DM's value is a null string.
<apll><pre>
      ⎕DM
 
      ⍴⎕DM  ⍝ In a CLEAR APL Workspace ⎕DM's value is an empty character vector
0
0
      +
SYNTAX ERROR
      +
      ∧
      ⍴⎕←⎕DM
SYNTAX ERROR
      +
      ∧
28</pre></apll>
<apll>⎕DM</apll> is a system variable. An APL error in the '''right argument''' of <apll>⎕EA</apll> will send a diagnostic message to <apll>⎕DM</apll>, as well as a '''triggering error event''' for <apll>⎕ELX</apll>.
See Also: [[System_Variable_ELX|⎕ELX]] and [[System_Function_EA|⎕EA]]


Quad DM(⎕DM) is a system variable. An APL error in the '''right argument''' of '''⎕EA will''' send a<br>
diagnostic message to ⎕DM, as will a '''triggering error event''' re ⎕ELX.<br><br>
See Also: [[System_Variable_ELX|Quad ELX or ⎕ELX]] and [[System_Function_EA|Quad EA or ⎕EA]]<br>
{{System Variables}}
{{System Variables}}
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Latest revision as of 13:05, 16 April 2018

⎕DM - Diagnostic Message

⎕DM Diagnostic Message set to last error message the APL interpreter encountered.
Unlike other system variables, ⎕DM cannot be assigned a value by the User. The APL interpreter sets its value when it encounters an error, e.g. DOMAIN ERROR.


⎕DM is set by APL to the last diagnostic error message the Interpreter encountered. It is for informational and diagnostic purposes only. User cannot set its value.

⎕DM is useful for viewing the last error message, particularly if Error Trapping is being used, or for system-function and user-function debugging purposes. For example: 

      ⎕DM

      ⍴⎕DM   ⍝ In a CLEAR APL Workspace ⎕DM's value is an empty character vector
0
      +
SYNTAX ERROR
      +
      ∧
      ⍴⎕←⎕DM
SYNTAX ERROR
      +
      ∧
28

⎕DM is a system variable. An APL error in the right argument of ⎕EA will send a diagnostic message to ⎕DM, as well as a triggering error event for ⎕ELX.

See Also: ⎕ELX and ⎕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


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