Conventions

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "This uses the QGIS_PREFIX environment variable we set earlier to tell QGIS where to find its resources."

A block of code is set as follows:

app = QApplication(sys.argv)

viewer = MapViewer("/path/to/shapefile.shp")
viewer.show()

app.exec_()

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

  def unload(self):
    self.iface.removePluginMenu("Test Plugin", self.action)
 self.iface.removeToolBarIcon(self.action)

Any command-line input or output is written as follows:

export PYTHONPATH="$PYTHONPATH:/Applications/QGIS.app/Contents/Resources/python"

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "If you haven't already installed QGIS, click on the Download Now button on the main QGIS web page to download the QGIS software."