ObjectScript

Hi guys!

Portrait of  Madame X, Gustave Caillebotte.

One of the features I like in InterSystems ObjectScript is how you can process array transformations in a specific method or a function.

Usually when we say "process an array" we assume a very straightforward algorithm which loops through an array and does something with its entries upon a certain rule.

The trick is how you transfer an array to work with into a function. 

One of the nice approaches on how to pass the information about an array is using $Name and Indirection operator. 

Below you can find a very simple example which illustrates the thing.

After many sleepless nights it's a pleasure to announce the newer, better, moderner ObjectScript compiler which implemented pretty much everything you ever wanted to have in modern ObjectScript:

• Design objective of this new compiler is to parse reasonable subset of current ObjectScript syntax which will look readable for stranger, and not scare them with 1 letter syntax. The good start for compiler was the old-good COS Guidelines from here https://github.com/intersystems-ru/cos-guidelines
• For reasons we mentioned above we do not parse 1 letter syntax. It's declared evil;
• We do not handle dotted syntax for the same reason - modern syntax with {} is proper replacement for dotted syntax blocks;

But we not only parse the modern ObjectScript syntax, we have implemented finally the long-standing request which we always dreamed about. Closures!

ObjectScript has at least three ways of handling errors (status codes, exceptions, SQLCODE, etc.). Most of the system code uses statuses but exceptions are easier to handle for a number of reasons. Working with legacy code you spend some time translating between the different techniques. I use these snippets a lot for reference. Hopefully they're useful to others as well.

�

In recent discussion on CachéQuality I was (friendly) blamed for old syntax promotion and deliberate obfuscation of the code. Therefore I decided to clarify my point and shed some light on one of possible source of side effects that may unexpectedly occur with RETURN command with an argument.

ˮ This is one of my articles which was never published in English. Let's fix it!

Hello! This article is about quite a practical way of developing InterSystems solutions without using the integrated tools like Studio or Atelier. All the code of the project can be stored in the form of "traditional" source code files, edited in your favorite development environment (for example, Visual Studio Code), indexed by any version control system and arbitrarily combined with many external tools for code analysis, preprocessing, packaging and so on

Recently I needed a classmethod that returns annotation value based on a name of a activity.

As doing it at runtime seemed inefficient, I wrote compile-time utility that iterates over all business process activities and generates relevant code.

This code could be used in a variety of situations when you need to iterate over business process activities, just add it as a secondary superclass to your BPL processes.

This code snippet sends an XML request to a server and saves the response to a file. The class method "test" runs the code:

Class objectscript.postXML
{
    classmethod test() {
        Set HTTPRequest = ##class(%Net.HttpRequest).%New()
        Set HTTPRequest.ContentType = "text/xml"
        Set HTTPRequest.NoDefaultContentCharset = 1
        Set HTTPRequest.Location = "ITOMCZ"
        Set HTTPRequest.Server = "wph.foactive.com"
        Do HTTPRequest.RemoveHeader("User-Agent")  
        Do HTTPRequest.RemoveHeader("Accept-Encoding") 
        Do HTTPRequest.RemoveHeader("Connection")
        Do HTTPRequest.SetHeader("Expect","100-continue")
     
        Set RequestXML = ##class(%Library.File).%New("c:\test.xml")
        Do RequestXML.Open("RS")
        Do HTTPRequest.EntityBody.CopyFrom(RequestXML)
        Do RequestXML.%Close()
     
        Do HTTPRequest.Post(HTTPRequest.Location)
     
        Do $System.OBJ.Dump(HTTPRequest)
        Do $System.OBJ.Dump(HTTPRequest.HttpResponse)
     
        Write HTTPRequest.HttpResponse.Data.Size
        Write HTTPRequest.ContentLength
     
        Set ResponseStream = ##class(%Stream.FileBinary).%New()
        // Second part is typically the file extension, i.e.: application/pdf -> pdf
        Set FileType = $Piece(HTTPRequest.HttpResponse.GetHeader("CONTENT-TYPE"),"/",2)
        Set ResponseStream.Filename = "C:\test."_FileType
     
        Write ResponseStream.CopyFrom(HTTPRequest.HttpResponse.Data)
     
        Write ResponseStream.%Save()
        Do ResponseStream.%Close()
    }
}

Here's a link to the code on GitHub

The following code walks a DOM using %XML.Node. It also prevents %XML.Writer to change whitespace. Run the code using the class method "test":

Class objectscript.walkDOM Extends %Persistent
{
    ClassMethod dfs(node As %XML.Node)
    {
        s entrynode=node.NodeId
        do {
        //element nodes with one whitespacetyped child are the ones we want to change
        if (node.NodeType=$$$xmlELEMENTNODE){
            s snode=node.NodeId     
            if (node.MoveToFirstChild())            
                {
                    i ('node.MoveToNextSibling()){
                        i (node.NodeType=$$$xmlWHITESPACENODE){
                            s node.NodeType=$$$xmlTEXTNODE
                            s node.NodeId=snode
                        }
                    }
            }
            s node.NodeId=snode     
        }   
        if (node.HasChildNodes()){
            d node.MoveToFirstChild()
            d ..dfs(node)
        }
        } while (node.NodeType'="" && node.MoveToNextSibling())
        s node.NodeId=entrynode
         
    }
     
    ClassMethod test()
    {
      set xml = "abcdefg"
     
      s reader=##class(%XML.Reader).%New()
      do reader.OpenString(xml)  
      set writer = ##class(%XML.Writer).%New()
      //do some magic
      d ..dfs(reader.Document)
       
      w !,"with indent=1:",!
      set writer.Indent = 1
      do writer.OutputToString()
      do writer.Document(reader.Document)
      w writer.GetXMLString()
      set writer.Indent = 0
      w !,"with indent=0:",!
      do writer.OutputToString()
      do writer.Document(reader.Document)
      w writer.GetXMLString()
    }
}

Here's a link to the code on GitHub: https://github.com/intersystems-community/code-snippets/blob/master/src/...

This article was written as an attempt to share the experience of installing the InterSystems Caché DBMS for production environment.
We all know that the development configuration of a DBMS is very different from real-life conditions.
As a rule, development is carried out in “hothouse conditions” with a bare minimum of security measures, but when we publish our project online, we must ensure its reliable and uninterrupted operation in a very aggressive environment.

The process of installing the InterSystems Caché DBMS with maximum security settings

OS security settings

The first step is the operating system. You need to do the following:

Here's a fun test to see how well you know ObjectScript.

What will each of the following statements output?

write 5 * 10 + 1

write 1 + 5 * 10

write 1 + 0 / 10

write 0 && 0 = 0

write 0 = 0 && 0

write 1 && 1 = 1

write 1 = 1 && 1

write 2 && 2 = 2

write 2 = 2 && 2

write "1 APPLE" + "2 BANANAS"

write "-1" + "1-2"

write +"+-+-+-5"

write "1D7P"-1

write "1E6F"-1

write 0 = "FOO"

write 0 = +"FOO"

write 0 = ''"FOO"

write "10X" - " 5" - "5"

write "10-5"

write +"10-5"

write @"10-5"

write 5_"1"-1

write "5"-1_"1"

write 10 + 10 > 21 + 1

Scroll down to see how many you got right...

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(Originally posted to InterSystems CODE by @Dmitry Maslennikov)
The following code snippet outputs message header data in Ensemble. The class method "fetchExecute" runs the process, and the result is stored in the argument "qHandle"

The following code provides information about software builds. Read the original description below for information about the different methods:

This code snippet contains the class method "test" which sends an HTML email. Change the literal strings in the method to customize the email's from address, to address, subject, and body:

Class objectscript.sendEmail Extends %RegisteredObject
{
    classmethod test() {
        set m=##class(%Net.MailMessage).%New()
        set m.From="user@company.com"
         
        set m.IsHTML=1
         
        do m.To.Insert("user@company.com")
        set m.Subject="Sent by IRIS mail"
        set m.Charset="iso-8859-1"
        do m.TextData.Write("<HTML><HEAD><TITLE></TITLE>"_$char(13,10))
        do m.TextData.Write("<META http-equiv=Content-Type content=""text/html; charset=iso-8859-2""></HEAD>"_$char(13,10))
        do m.TextData.Write("<BODY><FONT face=Arial size=2>Test <B>Test</B></FONT></BODY></HTML>")
        set s=##class(%Net.SMTP).%New()
        set s.smtpserver="mail.company.com"
        set status=s.Send(m)
    }
}

Here's a link to the code on GitHub

The following class method "test" contains code that can create a new class, create new properties for classes, or create new methods for classes. "test" runs all three of these processes once, and the code that performs each action is labelled by comments in the method:

ClassMethod test() As %Status
{
    set sc = $$$OK
    
    // Create a class
    set class = ##class(%ClassDefinition).%New("MyClass")
    set class.Description = "This is my test class"_$c(13,10)_"testing %ClassDefinition"
    set class.Super = "%Persistent"

    // Create a property and add it
    set property = ##class(%PropertyDefinition).%New("MyClass.MyProperty")
    set property.Type = "%String"
    set property.Description="This is a property"
    set sc1 = class.Properties.Insert(property)
    do:$$$ISERR(sc1) $system.Status.DisplayError(sc1)
    set sc = $$$ADDSC(sc, sc1)
    
    // Create a method and add it
    set method = ##class(%MethodDefinition).%New("MyClass.MyMethod")
    set method.ReturnType = "%Integer"
    set method.FormalSpec = "x:%Integer,y:%Integer=10"
    set method.Description = "Return product of x and y"
    set method.CodeMode = "code"
    set method.Code = " new result"_$c(13,10)_" set result=x*y"_$c(13,10)_" quit result"
    set sc2 = class.Methods.Insert(method)
    do:$$$ISERR(sc2) $system.Status.DisplayError(sc2)
    set sc = $$$ADDSC(sc, sc2)
    
    // Save the class definition
    set sc3 = class.%Save()
    do:$$$ISERR(sc3) $system.Status.DisplayError(sc3)
    set sc = $$$ADDSC(sc, sc3)
    
    return sc
}

Here's a link to the code on GitHub