User Commands in Dyalog APL

By Dan Baronet

A programmer's tool - V1.03

ProcedureThis tutorial is divided into 4 areas:- Why UCMDs and introduction- Dyalog's UCMDs- implementation of the UCMD

framework- Your UCMDs: how to write them

WhyThe idea is to provide a mechanism

for accessing tools anywhere by- separating utilities from the

common workspace- make them available at any time

HistoryThe concept of user commands

(UCMDs) is not new.APL/PC had them in the 90s.Some IPSharp users had them

(through S-Tasks)Their implementation was different

but the idea was the same

User Commands A user command (UCMD) is similar to a

system command like )LOAD or )WSID.It is a call to an independent routine

written by a user, not a routine provided by the system.

System commands start with a ), e.g. )SAVE

User commands start with a ], e.g. ]WSLOC

User Commands - syntax Like their system commands

counterpart, user commands may take arguments, e.g.)WSID [newname]

And]FNSLIKE [pattern]

Like system commands they are not case sensitive.

User Commands - syntax Unlike system commands, in the

actual implementation, they can also take modifiers, e.g.]FNSLIKE [Pattern] –format

Modifiers are preceded by a specific character (here -)

Modifiers ARE case sensitive.

User Commands - syntax This is Dyalog's implementation.

In fact, UCMDs could take any format

WE decide what is acceptable

User Commands Dyalog comes pre-packaged with a

set of user commands divided into groups.

Groups exist for SALT, workspace utilities, code utilities, user commands management, etc.

User Commands For example the command ]SAVE ,

which saves an OBJECT (not a workspace), takes up to 2 arguments, saving the object named in the 1st argument to, if present, the location named in the 2nd argument. Ex:

]save myfn \my\location\myfn

To bring the object back use the command ]LOAD:

]load my\location\myfn

User Commands - Help General help can be obtained with

]??The list of all commands can be obtained with

]? And ]?+Specific help for a command can be obtained

with]?cmdx

Or more detailed help, if any, with]??cmdx

Or]?\path\to\file\containing\a\user\cmd

User Commands availableDyalog comes pre-packaged with some

already defined UCMDsThey are divided into some 7 groups:- SALT- Spice (UCMD)- Svn- Sysmon- Tools- Transfer- wsutils

Group SALTThese are the same as their SALT functions:- Save object [tolocation]- Loadlocation- Compare file1 [file2]- Settings [type [value]]- Explore [folder|file]- List [folder]- Snap tolocation- Removeversions file

Group SpiceThese are commands used to manage the

User commands system:- Uload command - Udebug ON|OFF- Uclean- Unew- Ureset- Uversion - Umonitor

Group svnThis group contains commands to mimic

SubVersion's commands:- svnci: commit changes- Svnco: check out- Svnadd/delete: add/delete new files- Svnstatus/resolve- Svndiff: show changes to a file- Svnimport/export- Svnupdate: bring in most recent changes

Group SysMonThis group is used to monitor the system:- APLMON: used to monitor expressions by primitive, ex:

]aplmon {+/1=⍵∨⍳⍵}¨⍳1000 –file=\tmp\data)LOAD APLMONInitMon '\tmp\data.csv'

- CPUtime: used to find CPU used for expressions, ex:]cputime {+/1=⍵∨⍳⍵}¨⍳1000

- Monitor: used to find lines consuming the most CPU

Group TransferThis group is used to move code in and

out of ATF files with- in/out

And move code in and out of "extended" files with code translation with

- inx/outx

Groups Tools & WSutilsThese 2 groups contain various utilities e.g.

to show a subset of names following a specific pattern or do function call analysis or search the workspace for strings of code/text:]fnslike GUI* -date=>20090307]fncalls MainProgram -details -treeview]wsloc \babc[∧\w]← -pattern -recursive

UCMDs - implementation• The code to run a UCMD is contained in a

class or namespace in a SALT (text, Unicode)file.

• That file may be host to several UCMDs• Command names are case insensitive, e.g.

‘find’ and ‘FIND’ call the same code• Switches names are case sensitive• UCMDs are grouped together, e.g. utilities

can be grouped under the group ‘wsutils’• The class or namespace must contain at least

3 public functions: ‘List’, ‘Run’ and ‘Help’

UCMDs - implementation• The ‘List’ function is used to gather

basic info displayed when using ]?+• The ‘Help’ function is used to

display more complete info when using ]?cmdx or ]??cmdx

• The ‘Run’ function is the one doing the work.

UCMDs - implementationThe whole framework is based on 2

things:

- SALT: used to read/write Unicode text files

- Spice: used to implement the rules of UCMDs

UCMDs – an exampleLet’s assume we have a simple function we wish to

call once in a while without having to copy/call/erase it each time:

calendar 3 Mars

S M T W T F S 1 2 3 4 5 6 7 8 9 10 11 12 1214 15 16 17 18 19 2021 22 23 24 25 26 2728 29 30 31

UCMDs – an exampleWe need to create a class with the 3 basic functions, the <List> function:

:Class dates⎕IO←1 ⋄ ⎕ML←1∇ r←List:Access Shared Public r←⎕NS ⍬⍝ Name, group, short description and parsing rules r.Name← 'cal' r.Group←'dates' r.Desc← 'returns the calendar for a given month' r.Parse←'' ∇

UCMDs – an exampleThe HELP function:

∇ r←Help dummy:Access Shared Public r←'Enter a month as argument' ∇

UCMDs – an exampleThe RUN function:

∇ r←Run(a1 a2):Access Shared Public 'calendar' ⎕CY 'myutils' r←calendar ⍎a2∇ :endclass

UCMDs – an exampleBecause each class may contain

more than one UCMD the HELP and RUN functions should really account for that.

UCMDs – an example• HELP function for more than one command:∇ r←Help Cmd:Access Shared Public:Select Cmd:Case 'cal'r← 'Enter a month as argument':Case 'other'… :EndSelect∇

UCMDs – an example• The RUN function for more than one

command:∇ r←Run(Cmd Args):Access Shared Public:Select Cmd:Case 'cal''calendar' ⎕CY 'myutils'r←calendar ⍎Arguments:Case 'other'…:EndSelect∇

UCMDs – ParsingIf automatic parsing of the arguments is desired the

system will look at the line given as argument, split the tokens on spaces and put the resulting vector of text vectors in variable 'Arguments' in a namespace.

That namespace will be given as the 2nd argument to the function <Run>.

To request parsing simply put in 'Parse' (in function <List>) the rules to follow, e.g. '3' to ensure 3 arguments.

If no parsing is desired simply leave 'Parse' empty.

UCMDs – Parsing• If we wish the system to check the number of arguments (here

1) for us we tell it in <List>:

∇ r←List:Access Shared Publicr←⎕NS¨1⍴⊂⍬⍝ Name, group, short description and parsing rulesr.Name← ⊂ 'cal' r.Group←⊂ 'dates' r.Desc← ⊂ 'returns the calendar for a given month'r.Parse← '1' ∇

In that case the 2nd argument in <Run> will contain a namespace:

UCMDs – Parsing∇ r←Run(Cmd a2):Access Shared Public:Select Cmd:Case 'cal''calendar' ⎕CY 'myutils'r←calendar ⍎1⊃a2.Arguments:EndSelect∇Function <calendar> can also/should be defined in

the class.

UCMDs – an example ]cal 3 Mars

S M T W T F S 1 2 3 4 5 6 7 8 9 10 11 12 1214 15 16 17 18 19 2021 22 23 24 25 26 2728 29 30 31

UCMDs – an exampleIf Parsing is enabled, entering the wrong

number of arguments will be refused:]cal

Command Execution Failed: too few arguments

]cal 2 3 Command Execution Failed: too many arguments

UCMDs locationThe location of user commands is preset

to Dyalog's folder SALT\Spice under APL's location, e.g.

C:\program files\Dyalog\V121\SALT\Spice

UCMDs locationThe location of UCMDs is one of SALT's

settings.To know what they are:

[]SE.SALT.Settings 'cmddir'

Or, as a UCMD:

]settings cmddir

UCMDs locationYou can reset it too.It follows the same rule as SALT's workdir setting,

i.e. it is a series of paths separated by semicolons, e.g.

\my\own\path;C:\program files\Dyalog\V121\SALT\Spice

For example, to add "\my\own\path" to the existing path:

(note the comma)

]settings cmddir ,\my\own\path

UCMDs location

You can set them manually or in Options/Configure…

UCMDs location

UCMDs locationSome commands are always there: Spice's

and SALT's

Doing (note NO comma)]settings cmddir \my\own\path

Will keep Spice and SALT's commands even though they have not been specified.

UCMDs – Advanced Topics

Debugging code]udebug ON|OFF

When debugging is OFF errors are reported in the calling environment:

Command Execution Failed: DOMAIN ERRORWhen debugging is ON errors are reported in

the class:DOMAIN ERRORcalendar[4] r←n÷month ∧

UCMDs – Advanced Topics

SwitchesThose can be specified in the Parse variable:They come in different forms:- Without a value: /sw- With a value: /sw=- Maybe with a value: /sw[=]The specification for each includes the

switch delimiter (here /)

UCMDs – Advanced Topics SwitchesA set of possible values may be specified, e.g./animal=cat monkey giraffeA set of possible characters can also be

specified:/vowel ∊ aeiouOr/vowel [∊] aeiouIf the switch can be specified without a value

UCMDs – Advanced Topics

Switches – Examples1. Switch time takes a value, switch PM

does not, switch delimiter is /:Parse ← '/time= /PM'2. Switch Prime may accept values 2, 3, 5

and 7, switch Octal accepts values made out of '01234567', delimiter is +:

Parse ←'+Prime[=]2 3 5 7 +Octal∊01234567'

UCMDs – Advanced Topics

Switches – ExamplesSwitches and number of arguments

are specified together. A command accepting 2 arguments and a switch offset with a value would be specified as:

Parse ←'2 -offset='

UCMDs – Advanced Topics

ArgumentsArguments are delimited by spaces.If an argument must contain spaces, or the

switch delimiter character or a quote, it should be surrounded by quotes. For example, if the switch delimiter is /, the following call will contain 4 arguments:]mycmd 'arg 1' '2001/4/5' OK "I'm" /lights=on

UCMDs – Advanced Topics Long Arguments

If a command accepts N arguments and the last argument may contain spaces then it may be unnecessary to quote the last argument simply by stating the command as "long". For ex, if command addrec accepts 3 arguments it could accept]addrec Joe Blow 42 main str

With Parse ←'3L'The arguments will be 'Joe' 'Blow' '42 main str'

UCMDs – Advanced Topics

Short ArgumentsIf a command accepts a maximum of

N arguments it can be specified as "short". For ex,

With Parse ←'3S'Any number of argument less than

or equal to 3 will be accepted.

UCMDs – Exercices1. Write a UCMD to display the time,

formatted2. Write a UCMD to display the time

in another city

]END