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diff --git a/README-hacking.md b/README-hacking.md index cf2e332..e836f36 100644 --- a/README-hacking.md +++ b/README-hacking.md @@ -409,6 +409,42 @@ project is designed to grow in this framework. +File modification dates (meta data) +----------------------------------- + +While git does an excellent job at keeping a history of the contents of +files, it makes no effort in keeping the file meta data, and in particular +the dates of files. Therefore when you checkout to a different branch, +files that are re-written by Git will have a newer date than the other +project files. However, file dates are important in the current design of +the template: Make uses file dates of the pre-requisits and targets to see +if the target should be re-built. + +To fix this problem, for this template we use a forked version of +[Metastore](https://github.com/mohammad-akhlaghi/metastore). Metastore use +a binary database file (which is called `.file-metadata`) to keep the +modification dates of all the files under version control. This file is +also under version control, but is hidden (because it shouldn't be modified +by hand). During the project's configuration, the template installs to Git +hooks to run Metastore 1) before making a commit to update its database +with the file dates in a branch, and 2) after doing a checkout, to reset +the file-dates after the checkout is complete and re-set the file dates +back to what they were. + +In practice, Metastore should work almost fully invisiablly within your +project. The only place you might notice its presence is that you'll see +`.file-metadata` in the list of modified/staged files (commonly after +merging your branches). Since its a binary file, Git also won't show you +the changed contents. In a merge, you can simply accept any changes with +`git add -u`. But if Git is telling you that it has changed without a merge +(for example if you started a commit, but cancelled it in the middle), you +can just do `git checkout .file-metadata` and set it back to its original +state. + + + + + Summary ------- |