Add instructions for using ccache

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​1cb5405

Add instruction for ccache

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​cfd681d	Minor cleanup
​b1f502e	Minor cleanup

[jdemeyer]

Can we please take this opportunity to clarify better that people really should use make instead of ./sage -b unless they know what they are doing. For example, your added paragraph seems to imply that it's fine to run just ./sage -b when switching branches. However, in many cases that will not work because of changes to packages.

The text should make it clear that you need to run make to compile Sage (or make build to skip the documentation). If you made changes only to Sage library files, you can use ./sage -b. When switching branches, usually you change more than that.

[jdemeyer]

To clarify a bit better what I mean:

1. The stuff you added about ccache really belongs with the part about make and not with sage -b.

2. Moreover, I would suggest to mention make first (so people become less drilled to use sage -b all the time) and sage -b after that.

For me, 1. must be fixed (hence needs_work), while 2. is an optional improvement that you may want to do.

[jhpalmieri]

Should these instructions go in the developer's guide at all? It might make more sense to put them in the installation guide, with a pointer from the developer's guide ("if you switch branches a lot, you might consider installing ccache: see ..."). The installation guide already has a very brief mention of ccache, for what that's worth.

[paulmasson]

Jeroen, the documentation as written is very clear on when to run sage -b and make. Since I'd assume it is mostly read by developers just getting started, the current order of instructions seems preferable to me. How many developers start out altering packages before Sage Python code?

I wanted my warning to be close to the statement "This should be quite fast", since that's what triggered the whole ​discussion for me. I can see now that inserting the warning in the middle of the section is confusing, so I'll move it to the end. That way it will apply to all of the rebuilding cases described above it.

John, the installation guide doesn't make clear why one would want to install ccache. The only reason I did is because I regularly switch branches when working on tickets. That's a development issue, not an installation issue, so I think it belongs here.

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​82e686e

Add instructions for ccache

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​afdd559

Minor cleanup

[mkoeppe]

typo Recynthonization -> Recythonization

[jdemeyer]

Replying to paulmasson:

How many developers start out altering packages before Sage Python code?

Almost everybody does! But, just like you, they do not realize that changing branches often means changing packages. That is exactly the problem with the current documentation (although I agree that this is orthogonal to this ticket).

[jdemeyer]

Nitpick: I do not think that WARNING is correct here. Can you make it a NOTE instead?

[jdemeyer]

Apart from this last nitpick, this is good for me.

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​0161c5c

Corrections

[paulmasson]

Done.