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#Code Snippet

7

Code snippet is a programming term for a small region of re-usable source code, machine code, or text.

Article
· Mar 28, 2017 2m read
Map, Reduce and Filter Collections

Inspired by the article "Declarative development in Caché" that's still trending on the dev com. The OP explored a functional style of iterating over a collection. A comment today suggested "Caché would need syntax support for anonymous functions".

With Macros you can kind of get anonymous like syntax using dot notation.

This is not production code, but it does work. First the macros...

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A feature I recently used in working on ISC internal applications is the ability to send emails on behalf of someone. This is useful when generating system notifications from an application when you want some of them to show up as being from a specific person, perhaps posting comments on a work ticket.

In my case I was updating our facilities work order system for tracking requests. Normally all notification emails are sent from the same noreply email address. I wanted to change that so comments added from the original requester would show up as being from them and stand out.

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Article
· Mar 2, 2017 1m read
Trusting the code you import

As more people join Developer Community, and with increasing efforts to promote code sharing, I'd like to draw fresh attention to this post I wrote a year ago. It spotlights a feature within the class compiler which is both useful and dangerous. When importing code (e.g. from an XML export of classes received from someone), it's worth considering the risks.

Even if that post doesn't seem relevant to you at the moment you may wish to note it for the future. A handy way of doing this is to click the star icon at the end of it.

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This is the second part of my long post about package managers in operating systems and language distributions. Now, hopefully, we have managed to convince you that convenient package manager and rich 3rd party code repository is one key factor in establishing of a vibrant and fast growing ecosystem. (Another possible reason for ecosystem success is the consistent language design, but it will be topic for another day.)
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Points to remember before you start:

  1. It is not possible in a COS (Caché Object Script) job/process context to have multiple Named Pipes. It is a one Named Pipe per job/process limited line of communication.
  1. Named Pipes, in Caché, like most pipes on most operating systems are Unidirectional. That means you open them for either Read or Write, but not both.
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Article
· Feb 17, 2016 3m read
Listing files in folder

Question:

How do I get a list of files residing in a certain folder/directory, according to some wildcard/filter.

For example all '*.txt' files in 'C:\Temp'.

Answer:

In CACHE –

You can use the %Library.File's FileSet class query.

Here's some sample code using it (also attached):

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Hi, community!

Consider you need to exclude substring(s) from a string.

I did it with the following snippet:

/// excludes all the substrings from the string
ClassMethod ExcludeSubstring(substr,str as %String) As %String

{

 while ($L(str,substr)>1) {

 set str=$Piece(str,substr)_$Piece(str,substr,2,*)

            }

 quit str

}

So, for example:

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Environment: Cache for Windows (x86-64) 2015.2.2 (Build 811U) Thu Mar 3 2016 12:55:48 EST [HealthShare Modules:Core:14.01.351

When try the following to send back SOAP Fault, is the following correct way?

Set fault=##class(%SOAP.Fault).%New()
Set fault.faultcode=$$$FAULTServer
Set fault.faultstring="Processing Error"
Set fault.detail= "Error on server"
Do ..ReturnFault(fault)

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Here you have an easy way to write and execute COS code from your unix scripts. This way one does not need to write routines or even open Studio or Atelier. It can be an option for simple and small actions for instance things like installation tasks or compiling.

See sample bash script (compile.sh) to compile classes:

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Checking if Directory or File Exists:

Outlined below is an example of how to check if a directory exists:

Set directoryName="c:\temp\nosuchdir"

/* Check for existence of a directory - Return Value:  0 - directory does not exist;  1 - directory does exist  */

Set directoryExists=##class(%File).DirectoryExists(directoryName)

If ('directoryExists)  // do the processing for when a directory does not exist


Outlined below is an example of how to check if a file exists:

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We're developing Ensemble PoC and one day our frontend developer (who doesn't have Ensemble production running) said that Populate just doesn't cut it and he needs to see the real data. He needed only one object, but the problem was - it's a big object. Still, I checked ids of everything related and wrote this command (parts omitted, but you get the idea):

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Process-private Globals can be used as a data global in storage definition. That way, each process can have its own objects for the class with ppg storage. For example lets define a pool, which can:

  • add elements to a pool (ignoring duplicates)
  • check if an element exists in the pool

Here's the class:

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Cache tricks

Several years ago, long before Developer Community Portal was launched, I published a series of Caché tricks at one of Czech web sites. In this article, I’m posting translated version of one of them.

Capturing output of someone else’s methods or routines

Suppose you, or someone else created a useful method or routine, that was producing some computation that you’d like to benefit from, but the routine was writing output to process principal device.

You would like to use the data, but you need it not written to a device, but assigned to a variable. And, for any reason, you can’t modify the code. What can you do?

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Article
· Jul 18, 2016 15m read
Remote proxy objects via dynamic dispatch

This article created as side effect of preparations to the longer set of articles about simple, but still handy MapReduce implementation in Caché. I was looking for relatively easy way to pass arguments to (potentially) multiple targets via remote calling facilities. And after several attempts I have realized that we do have very powerful mechanism in the Caché ObjectScript which might be of particular help here – dynamic dispatch for methods and properties.

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Hi,

I am new to Cache and I am trying to convert a JSON string (msgdata) that contains a JSON payload to an object to be saved into a Driver. Entity table. I am running into 2 issues and would appreciate any help:

1) It seems that when the 1st element of a list within the payload (Choices) is an empty string, after I call %ConvertJSONToObject, the obj.%data("payload").Choices contains just 1 empty element, removing the next 3 valid values (10,20,30). The same does not happen if I change the input to [10,20,"",30], in this case it works correctly.

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