(I’m using google translate)
I separate my HTML and PHP, just for good programming practices in MVC.
However a lot of the time I come across someone on staff writing HTML directly in a PHP file.
And during the discussion of ‘don’t do that, it’s bad, it’s not a good practice’, I haven’t got any technical arguments, apart from ‘it’s not good practice’.
And they always say, ‘I am not bound to get stuck on details.”
Technically, because it isn’t recommended?
It is not recommended because the past has shown that the longer a routine or script grows, the harder it is to manage. If you need to deal with HTML and PHP in one file, you need to write more than if you would have separated the code into two. Which brings me to the point that you write more in one file with HTML and PHP which results in more complex code.
This is only general. There are programmers out there who don’t have a problem with larger code-chunks and who don’t have a problem with mixing languages in the same files.
At first sight it might even look easier. However, as software tends to become more complex as it grows, after some time of growth it’s worth to think about how to modularize the code, e.g. to separate the view from request processing.
One common line that is drawn between components is then between the output (display) and the processing. The processing will interface with the output layer then instead of having both jobs in one script/routine (processing and display of output). Actually the output is factually abstracted / normalized / reduced to make the output code work on it on it’s own. E.g. instead of outputting HTML to the browser, the processing will pass objects to the output layer and the output layer will convert it into HTML then (the meaning of object is broad here, can be a variable, an array or an OOP object).
If you are developing together with someone else, you should decide together where to draw these lines so you can actually work together. You’re both doing something wrong because like you write in your question it’s not clear how you can work together. Working together is more crucial than favouring one design over the other. If you think your colleague is wrong, you both need to discuss the issue.