I love this proposal! Just the other day I was playing with Yeoman Generator and they use a similar technique and it amazed me. They make things appear and disappear and change the previous contents, for example when asking several consecutive questions:

this is clearly lacking tests.

@stof The todo at the end of the description says that tests still needs to be added

Only first example works properly for me. It also works based on a viewport, I don't think that's by purpose

//edit: it has been fixed, removed images as they took too much space

@ostrolucky Can you please try the examples again, there was some missing changes that I forgot to commit

It also works based on a viewport

A limitation with the console is that you can only manipulate anything in the viewport. So if any content stretches outside the viewport, it becomes extremely difficult (if not impossible) to modify the contents.

This kinda changes behaviour of Table helper. I don't think it's acceptable. Table helper without this patch doesn't redraw it's content. Calling

$table->render();
$table->render();

would normally output table twice, but this patch makes it erase first one and replace it with second one

Second thing is that ConsoleSectionOutput always appends newline to output.

Third thing, ProgressBar only works thanks to special patch. Anything other utilizing escape sequences won't work.

Trying to figure out how to make this universal.

The change in behaviour for the table helper is intented. The table is rendered in a section output, that can be modified. This adds a feature to the table helper where you can modify and re-render the table without rendering it twice. If you want the normal behaviour, just pass the normal console output instance to the table and not a sectioned output.

Second thing is that ConsoleSectionOutput always appends newline to output.

The newline at the end is currently a requirement, as it becomes difficult to navigate the console and change the contents without it. But I am working on a patch.

Anything other utilizing escape sequences won't work.

I'm not sure if we should cater for output with escape sequences. If a user wants to use escape sequences, they should just use the standard console output. If they want to modify the output, then they should use the section output.

This PR is not finished, there are a lot of edge cases and some missing functionality that I'm working on to solve, which I will push once it's done. Thanks for the feedback so far

@ostrolucky If the Table behavior is different only when using the new output class then that means Table just leverages the new feature. If passing the existing outputs gives the same result as before (reading the code I believe it does) then there is no issue.

@chalasr I still don't think this feature should affect behaviour of current components. Purpose of this feature is just ability to split screen to sections. How is forcing table to redraw itself related to that? Here is better example why is this wrong:

$table1->render();
$table2->render();

You would expect both tables to be shown on the screen. Instead, content of second table will overwrite content of first table, unless explicitly assigned different output section. I don't think this is expected. If you do this in a loop or have branching logic which determines if, when and which table is supposed to be outputted, you will quickly find out that this approach is unmaintainable.

Rest of my points are not so important, solving them would require to make implementation a lot more complicated, I was just not sure if they are important for you so wanted to brought them up. If they aren't, they aren't for me either.

@ostrolucky How will the second table overwrite the first one? If you use different output sections, they will still render both, as the table is only redrawn within it's own section. If you use the normal console output and not the new class, both tables will still be shown as it won't use the new functionality. So IMO there is no unexpected behaviour. The only missing part in this instance is that the new class doesn't take into account the output of the normal console. But that is one of the fixes I'm working on. So if you combine thr normal console output and the output of the new class, then you might run into some rendering issue, but that should be fixed soon

You didn't continue to read. I did mention that you if you want to avoid this, you must use different output sections and that's complicated when you have any kind of logic. For example:

$section1 = $output->section();
$section2 = $output->section();

$section2->writeln('some stuff');

while (true) {
    $table = new Table($section1);
    $table->setHeaders(['Stuff']);
    $table->addRow([$rand]);
    $table->render();
}

Now, how do I output contents of these tables above section2 without redrawing them? Now I am forced to manipulate with order of the sections container directly, because I have to create new output sections on the fly and push them in between.

Then just use $table = new Table($output); as you would normally have instead of using $output->section()

Last comments addressed and table bug fixed. I tested all the original examples and every one now works as expected.

@ostrolucky Thank you for all the effort in properly testing and reviewing this.

Status: Needs Review

Thank you @pierredup.