2.7: Saving, Quitting and Restarting a Pharo Session

Last updated
Save as PDF

Page ID: 39725

\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

You can exit Pharo at any point, by closing the Pharo window as you do any other application window. Additionally you can use the World Menu and select either Save and quit or Quit.

In any case, Pharo will display a prompt to ask you about saving your image. If you do save your image and reopen it, you will see that things are exactly as you left them. This happens because the image file stores all the objects (edited text, window positions, added methods... of course since they are all objects) that Pharo has loaded into your memory so that nothing is lost on exit.

When you start Pharo for the first time, the Pharo virtual machine loads the image file that you specified. This file contains a snapshot of a large number of objects, including a vast amount of pre-existing code and programming tools (all of which are objects). As you work with Pharo, you will send messages to these objects, you will create new objects, and some of these objects will die and their memory will be reclaimed (garbage-collected).

When you quit Pharo, you will normally save a snapshot that contains all of your objects. If you save normally, you will overwrite your old image file with the new snapshot. Alternatively, you may save the image under a new name.

As mentioned earlier, in addition to the .image file, there is also a .changes file. This file contains a log of all the changes to the source code that you have made using the standard tools. Most of the time you do not need to worry about this file at all. As we shall see, however, the .changes file can be very useful for recovering from errors, or replaying lost changes. More about this later!

It may seem like the image is the key mechanism for storing and managing software projects, but that is not the case. As we shall see soon, there are much better tools for managing code and sharing software developed by teams. Images are very useful, but you should learn to be very cavalier about creating and throwing away images, since versioning tools like Monticello offer much better ways to manage versions and share code amongst developers. In addition, if you need to persist objects, you can use several systems such as Fuel (a fast object binary serializer), STON (a textual object serializer) or a database.