Why Delphi for PHP should have used Prado instead of VCL

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I recently went to a presentation where some guys from CodeGear showcased Delphi for PHP and VCL4PHP. It’s a new product which enables PHP developers to use drag / drop and wysiwyg methods to build applications with PHP. The IDE uses VCL4PHP as the underlying framework.

This kind of tool is something that ASP.net has had for a long time (ie Visual Studio.net). Not only does it make the development process easier when it comes to building applications, but it also handles setup of applications, default configs etc. Until now there hasn’t been any tools for doing this with PHP, so I sincerely congratulate CodeGear on getting something out to the masses. Their IDE is a really nice tool with lots of potential. It ships with apache, and has lots of nice features like a integrated debugger etc. The immediate draw-back is that it runs on Windows only. My impression is that most PHP developers (atleast above hobby level) works on Linux based workstations, so I imagine getting a strong user base could prove to be difficult.

Now, why do I think that Prado is far superior to VCL, and why would it have been a better choice:

1.Exception handling
Any framework which are viable for larger scale application development should use exceptions. It’s an established way of controlling code flow and making sure the code can recover from error.

VCL: This is the first MAJOR flaw which would possibly be the hardest to fix. I’ve spent some time looking around in the VCL code, and there is some basic exception handling here and there. The problem is that most of the controls does not have any exception handling at all. This makes it very hard and tedious to control the follow when errors occur.

Prado: Usage of exceptions throughout the whole framework, with the possibility to have custom exception handlers lays the foundation implementing proper flows in the application and user friendly feedback when errors occur.

2. Usage with other PHP frameworks
A framework needs to play nice with other framework these days. There is no framework that has everything, so the coder will most likely use any given framework in addition to something else.

VCL: None of the controls I’ve seen while checking out the VCL source code are prefixed. Having controls with class names like ListView, PageControl, TreeNode etc won’t play nice with other frameworks. Also, using class names like Object and Component isn’t something you’d want to have in a framework.

Prado: All components in Prado are prefixed with a ‘T’ like TLabel, TPage, TListView ensures cooperation with other frameworks.

3. Generation of HTML code from controls
VCL: The controls implement a method called dumpContents which basically writes HTML and JavaScript tags and attributes by using echo. Some sub classing is done where the parent renders as well.

The following snip is taken from their CustomLabel code:
552 if (trim($this->LinkTarget)!=””) $target=”target=\”$this->LinkTarget\””;
553
554 $class = ($this->Style != “”) ? “class=\”$this->StyleClass\”” : “”;
555
556 echo “<div id=\”$this->_name\” $style $alignment $hint $class”;
557
558 if ($this->_link==””) echo “$events”;
559
560 echo “>”;
561
562 if ($this->_link != “”) echo “<A href=\”$this->_link\” $target

By letting most of the controls be responsible for writing the low-level HTML code it’s much harder to keep the code XHTML valid, and does not exactly scream re-use. See next point for how Prado handles this.

Prado: Controls that render contents in Prado extends TWebControl. I’d like to quote the Prado manual for TWebControl here:
“TWebControl is the base class for controls that share a common set of UI-related properties and methods. TWebControl-derived controls are usually associated with HTML tags. They thus have tag name, attributes and body contents. You can override getTagName to specify the tag name, addAttributesToRender to specify the attributes to be rendered, and renderContents to customize the body content rendering. TWebControl encapsulates a set of properties related with CSS style fields, such as BackColor, BorderWidth, etc.

Subclasses of TWebControl typically needs to override addAttributesToRender and renderContents. The former is used to render the attributes of the HTML tag associated with the control, while the latter is to render the body contents enclosed within the HTML tag.”

4. XHTML code generation
Producing valid XHTML is something we should all strive to do. Not doing so may result in display problems in most browsers.

VCL: I tried to validate a basic demo site created with Delphi for PHP and VCL4PHP. The results speaks for them selves. The generated HTML code is not XHTML compliant. Example from the CustomLabel code again – echo “<A href=\”$this->_link\” $target. Remember that XHTML tags are always lowecase. There are several other problems as well, and the validation link shows some of them.

Prado: The HTML code that Prado generates is mainly done in the parent controls, so keeping the base implementations XHTML valid mostly ensures that the child controls will be as well. This also removes the actual rendering code from the controls, so creating new controls is far easier and cleaner.

5. Validation controls
Input validation is some of the most boring tasks when writing web applications, and it can be fairly difficult to get it right.

VCL: According to the guy from the presentation there is none, but I found a screen cast here. It seems way more tedious than the Prado way, and I can’t tell if it’s released or just in trunk / testing at the moment.

Prado: Prado ship with several validation controls which works both client side and server side. TRequiredFieldValidator, TRegularExpressionValidator and TEmailAddressValidator ensure that the coder can feel very safe when it comes to validating input. TCustomValidator lets the user create custom validation logic to perform tasks (for example login checks). A complete list and usage examples can be found here.

6. Encapsulation
Encapsulation is a way to make sure that the internal state of classes isn’t messed with by code that should not be able to.

VCL: I’ve been looking trough the code trying to find controls that actually use private methods for managing their internals. As far as I can see there is only a fraction of the controls which uses private methods, and when they do it’s only for one or two methods. This is a design no-no when everyone can call everything.

Prado: Only methods which have to be public are public. This ensures proper encapsulation and prevents the coder from accidentally messing up the state of a control.

7. Component properties

VCL: Delphi for PHP stores all component properties in XML files. I see the point of doing this for the sake of the IDE, but when it comes to runtime code I do not. During the demo they showcased how to use smarty templates with VCL, and to add a control which was created in the RAD gui they use markup ala {button1}.

Prado: Prado separates the code and login into two files (.php which holds the page class, and .page which holds the markup). The properties for the components are kept in the .page files which is a much easier way to look at the controls when creating markup. Check this link for a quick intro to how Prado handles this.

8. Usage of globals
VCL: Using globals? We all know this is bad and belongs pretty much belongs in PHP4 applications. If you need a dirty hack it can be a last resort kind of thing, but using it throughout the whole framework?

Example of globals usage:
30 $exceptions_enabled=true;
31
32 global $use_html_entity_decode;
33
34 $use_html_entity_decode=true;
35
36 global $output_enabled;
37
38 $output_enabled=true;
39
40 global $checkduplicatenames;
41
42 $checkduplicatenames=true;

183
184 /**
185 * Global $application variable
186 */
187 $application=new Application(null);
188 $application->Name=”vclapp”;
189

These things should be config related and stored in either the application object or a core base class.

I also checked out the blog demo from this page, and usage of globals can be found throughout the applications (global $BlogDB, global $AdminDeleteComment etc).

Prado:
Prado uses globals in one single file, and that’s the file responsible for generating client side scripts. Settings which span the whole application can usually be accessed from the application object.

9. Ajax

I’m considering to do another post comparing the ajax features in depth, but I just wanted to point out one thing seen in this screencast on AJAX. The coder escapes from PHP to write the javascript, then jumps back into PHP. In Prado things like these follow the same design as the rest of the framework.

Conclusion

I want to do some more in depth comparisons of controls and ajax support later on, but my current impression of VCL4PHP is that it’s “out of date” or not quite on a professional level. Not taking advantage of PHP5 features like interfaces and encapsulation, lacking proper exception handling, key features like validation and not generating valid XHTML code are all major points which I would expect a proper framework to have in place. One has to wonder why CodeGear went in this direction.

If you consider using VCL / Delphi for PHP I recommend that you first stop by the VCL4PHP forums to get some impressions on how people are using it and see their experiences.

I would really like to come in contact with someone that knows VCL4PHP so that a in depth comparison of the different controls can be done.

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