Compiler

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On the back of my recent post on writing bug-less code I wanted to raise a few suggestions (to ISC) that would help prevent certain types of bugs at compile time. I've probably missed a few, but these are the main ones in my mind. Please contribute more suggestions.

Btw, these also serve as potential gotchas for new COS developers.

I except that introducing these types of changes can cause legacy code problems. Particularly where developers do some interesting overloading of method arguments. Therefore I would see these as an option that would need to be enabled and that it won't prevent compilation (it would warn not error).

As an alternative I could see these being implemented as a Lint tool. This is something I (and perhaps the community) would be willing to do if we had an open source AST tree as a starting block (if anyone is aware of one in existence for COS)

Last comment 18 April 2017
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I have classes A and B, B derived from A, A has method Abc.

From INT of class B I see that compiler copies implementation of Abc to class B, so that Abc exists both in A and B.

As result, when B invokes Abs, B.Abs() is executed instead of A.Abs(). In result debuger is not able to step into Abs and breakpoints in A.Abs never hit.

Why this happens and how can I avoid this?

Update:

OK, now I know the reason: compiler makes the copy if Abc has this line:

cn=##Expression($$$quote(%classname))

hmmmm... compiler needs name of method's class so it "moves" the method to child class. Well, perhaps there is a good reason for that but for the moment the solution looks strange

Last answer 12 April 2017 Last comment 12 April 2017
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Due to a new project I'm getting involved inside %Installer stuff deeper than ever I'd be happy to. Most of it was pretty easy to get, thanks to documentation, articles and SAMPLES example, while I can't dig good solution for one problem. I'm trying to import and compile some classes, willing to ignore two types of errors: 5202 (NothingToCompile) and 5373 (PredecessorClassDoesNotExist - a normal case when SNMP sampling class is compiled for the 1st time, before it was registered). 

I've tried the following:

Last answer 28 March 2017 Last comment 28 March 2017
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In my previous article, we reviewed possible use-cases for macros, so let’s now proceed to a more comprehensive example of macros usability. In this article we will design and build a logging system.

Logging system

Logging system is a useful tool for monitoring the work of an application that saves a lot of time during debugging and monitoring. Our system would consist of two parts:

  • Storage class (for log records)
  • Set of macros that automatically add a new record to the log

Last comment 24 March 2017
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The class %Compiler.UDL.TextServices arrived in 2015.1, bringing us methods for exporting a class in UDL format (i.e. looking just like we're used to seeing it in Studio), and importing a UDL format definition back into a namespace. Some source control tools including our Deltanji are now able to use UDL format, resulting in diffs that are easier to understand.

Last comment 1 February 2017
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Hi all!

I'm developing a mini-framework to implement annotations in Cache. I want to support two kind of annotations: metadata and method decorators. I've got stuck trying to implement the second one.

Metadata

With metadata annotations I can add metadata to any kind of target. A target can be a method/classmethod, parameter, property and class.

For example

Last answer 25 January 2017 Last comment 26 January 2017
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Class Queries in InterSystems Caché is a useful tool that separates SQL queries from Caché Object Script code. Basically, it works like this: suppose that you want to use the same SQL query with different arguments in several different places.In this case you can avoid code duplication by declaring the query body as a class query and then calling this query by name. This approach is also convenient for custom queries, in which the task of obtaining the next row is defined by a developer. Sounds interesting? Then read on!

Last comment 9 December 2016
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As a developer, you have probably spent at least some time writing repetetive code. You may have even found yourself wishing you could generate the code programmatically. If this sounds familiar, this article is for you!

We'll start with an example. Note: the following examples use the %DynamicObject interface, which requires Caché 2016.2 or later. If you are unfamiliar with this class, check out the documentation here: Using JSON in Caché. It's really cool!

Example

You have a %Persistent class that you use to store data. Now, suppose that you are ingesting some data in JSON format, using the %DynamicObject interface. How do you map the %DynamicObject structure to your class? One solution is to simply write code to copy the values over directly

Last comment 22 November 2016
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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:

#!/bin/bash
#####################################################################
# Script to compile classes
# $1 = NAMESPACE
# $2 = ClassName
#
# For example:
# ./compile.sh "SAMPLES" "Sample.Person" 
#####################################################################
echo -n "username:"
read username
echo -n "password:"
read pwd

csession HSINSTANCE -U "$1" <<EOFF
$username
$pwd
set status = \$SYSTEM.OBJ.Compile("$2")
h
EOFF

This is the output from the console

Last comment 14 October 2016
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I'm new to Cache and trying to follow the Using Cache Studio PDF. In section 2.4.3(Adding a Zen form) it tells you insert the following code;

<button caption="Save" o select="zenPage.saveRecord();" />

Unfortunately that code fails compilation. If you try and use the tools there is no o select option nor a select or onselect option. I was wondering if anyone has used this PDF before and knows what the correct attribute should be?

 

Last answer 15 July 2016 Last comment 14 July 2016
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I have the following problem:

  • There are several classes with method generators, which needs to be compiled during every compilation
  • I have "ckub" qualifiers enabled in studio
  • I don't want to remove "u" qualifier because I need it very much in another namespaces

So how do I force classes with method generators to recompile when "u" qualifier is present?

Last comment 15 July 2016
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Greetings! This article describes yet another simple way of creating installers for the solutions based on InterSystems Caché. The topic covers applications, which can be installed or completely removed from Caché with one action only. If you are still documenting installation instructions that have more than one step to do to install your application — it’s high time you automated this process. 

Last comment 10 May 2016
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Here's my code (download):

Class Utils.Generators [ Abstract ]
{

ClassMethod B()
{
    s ^a = 1
}

ClassMethod A() [ CodeMode = objectgenerator, GenerateAfter = B, PlaceAfter = B ]
{
    k ^a
    do ..B()
}

Now, obviously for it to work I need method B compiled and ready to use before compiling method A().

I test it with the following code:

do $system.OBJ.UnCompile("Utils.Generator")
do $system.OBJ.Compile("Utils.Generator")

Yet, I receive the following compilation error

Last answer 10 April 2016 Last comment 10 April 2016
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[SOLVED]

added 

>/tmp/compilew.log &>/tmp/compilew.log ; tail /tmp/compilew.log

to redirect the output to the stdout. Somehow the javac has wierd behavior with the output on errors and verbose information.

Hi,

i want the JAVA-Projections and wrappers to compile after Caché created the files. The creation of the files works 100%.

My addition to createProjection in our Projectionclass is following

Last comment 15 March 2016
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So another topic that has been of interest to a number of people since the beta was put up last week is in regard to Studio Hooks and Atelier. This requires a bit of background and then some discussion of how the architecture of Atelier necessitates some changes and then what our current thinking on the subject is.

Studio hooks were added to Cache over 10 years ago. They have two primary usages. The first is that on an appropriate action such as creating a new document, or compiling a document a callback is executed whose job is to interact with external source control systems. This is done by writing COS scripts that “do the right thing” for a given source control system based on the callback invoked. All of this code ran on the server and used all the facilities available on the server such as locks and transactions etc

Last comment 3 March 2016
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Is the default language (i.e., $$$DefaultLanguage, which is used as the basis for localization with $$$Text/etc. at compile time) always "en" for new Caché installations, or could it be different? How is this determined? I don't see an option to select a language during Caché installation.

Also, is there a supported/preferred API for setting the default language? Looking at %occMessages.inc, one option would be:

Set $$$DefaultLanguageNode = "en"

But I'd expect there to be a classmethod for this somewhere (and haven't managed to find it yet)

Last comment 2 March 2016
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The attached file contains an example of code generation using ObjectGenerators which builds a very simple homemade RuleEngine. 

Code generation is an excellent way of increasing performance moving run-time calculations to compile-time.

We could generate code creating routines or implemeting methods using ObjectGenerators. In this example we are using ObjectGenerators.

Update: Rule Engine is now on GitHub https://github.com/intersystems-ib/cache-iat-ruleengine

A very simple code generated method

For starters, let's begin with a very basic code generated method

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