Documentation for Magento2.Templates.ThisInTemplate rule

[ihor-sviziev]

Description

Right now the only one option to use helpers inside blocks - is following code:
$this->helper(<helper_class>), but this Magento2.Templates.ThisInTemplate rule complains against it. As result - we have to add to ignore Magento2.Templates.ThisInTemplate in many view files.

Examples:
Try to find "Magento2.Templates.ThisInTemplate" in following commit:
magento/magento2@514e3d0

Expected behavior

We should not have any complains from static tests when running valid code

Benefits

We will not have useless disabling of this rule

Additional information

Option 1: this code example should be added to exception list
Option 2: there should be developed or provided recommended solution how to avoid it

[lenaorobei]

@ihor-sviziev thanks raising this question.

First of all we need to define correct recommendation here. On the one hand the use of helpers is in general discouraged, on the other hand we have legacy code that requires significant refactoring in order to archive this.

Do we want to change sniff behavior and allow $this->helper(<helper_class>) or we want to suppress such line for now and refactor in future?

Would you be interested in raising this question during the next architecture discussion?

[ihor-sviziev]

Hi @lenaorobei,
Unfortunately I'll not be able present on next architecture discussion. Could you raise this question instead of me?
Thank you

[lenaorobei]

Sure, I'll do that.

[lenaorobei]

This issue was discussed during architecture discussion magento/architecture#183. Notes:

• The use of helpers is in general discouraged.
• Magento2.Templates.ThisInTemplate rule should remain the same.
• $this->helper(<helper_class>) code should be refactored, blocks should contain all necessary dependencies.
• ViewModel should be used.

I suggest adding documentation forThisInTemplateSniff.md like ForeachArrayMergeSniff.md and describe this recommendation.

I'm going to change purpose of this ticket to adding .md page with How to Fix section.
Extended message can be added to the rule output as well.