A Beginner's Guide to Using pyGTK and Glade
In your button1_clicked() function, replace the print statement with:
Now, whenever you click GO! the results are displayed in your window. By dividing your main window with a set of vertical panes, you can resize this window, if you like (Figure 9).
Unlike GTK v1, under GTK v2 a tree and a list basically are the same thing; the difference is the kind of store each of them uses. Another important concept is the TreeIter, which is a datatype used to store a pointer to a particular row in a tree or list. It doesn't offer any useful methods itself, that is, you can't ++ it to step through the rows of a tree or list. However, it is passed into the TreeView methods whenever you want to reference a particular location in the tree. So, for example:
import gobject self.treeview=self.wTree.get_widget("treeview1") self.treemodel=gtk.TreeStore(gobject.TYPE_STRING, gobject.TYPE_STRING) self.treeview.set_model(self.treemodel)
defines a tree model with two columns, each containing a string. The following code adds some titles to the top of the columns:
self.treeview.set_headers_visible(gtk.TRUE) renderer=gtk.CellRendererText() column=gtk.TreeViewColumn("Name",renderer, text=0) column.set_resizable(gtk.TRUE) self.treeview.append_column(column) renderer=gtk.CellRendererText() column=gtk.TreeViewColumn("Description",renderer, text=1) column.set_resizable(gtk.TRUE) self.treeview.append_column(column) self.treeview.show()
You could use the following function to add data manually to your tree:
def insert_row(model,parent, firstcolumn,secondcolumn): myiter=model.insert_after(parent,None) model.set_value(myiter,0,firstcolumn) model.set_value(myiter,1,secondcolumn) return myiter
Here's an example that uses this function. Don't forget to add treeview1 to your glade file, save it and copy it to your local directory:
model=self.treemodel insert_row(model,None,'Helium', 'Control Current Helium') syscallIter=insert_row(model,None, 'Syscall Redirection', 'Control Current Syscall Proxy') insert_row(model,syscallIter,'Syscall-shell', 'Pop-up a syscall-shell')
The screenshot in Figure 10 shows the results. I've replaced the TextView with a TreeView, as you can see.
A list is done the same way, except you use ListStore instead of TreeStore. Also, most likely you will use ListStore.append() instead of insert_after().
A dialog differs from a normal window in one important way—it returns a value. To create a dialog box, click on the dialog box button and name it. Then, in your code, render it with gtk.glade.XML(gladefile,dialogboxname). Then call get_widget(dialogboxname) to get a handle to that particular widget and call its run() method. If the result is gtk.RESPONSE_OK, the user clicked OK. If not, the user closed the window or clicked Cancel. Either way, you can destroy() the widget to make it disappear.
One catch when using dialog boxes: if an exception happens before you call destroy() on the widget, the now unresponsive dialog box may hang around, confusing your users. Call widget.destroy() right after you receive the response and all the data you need from any entry boxes in the widget.
Some day, you probably will write a pyGTK application that uses sockets. When doing so, be aware that while your events are being handled, the application isn't doing anything else. When waiting on a socket.accept(), for example, you are going to be stuck looking at an unresponsive application. Instead, use gtk.input_add() to add any sockets that may have read events to GTK's internal list. This allows you to specify a callback to handle whatever data comes in over the sockets.
One catch when doing this is you often want to update your windows during your event, necessitating a call to gtk.mainiteration(). But if you call gtk.mainiteration() while within gtk.mainiteration(), the application freezes. My solution for CANVAS was to wrap any calls to gtk.mainiteration() within a check to make sure I wasn't recursing. I check for pending events, like a socket accept(), any time I write a log message. My log function ends up looking like this:
def log(self,message,color): """ logs a message to the log window right now it just ignores the color argument """ message=message+"\n" self.logwindow.insert_at_cursor(message, len(message)) self.handlerdepth+=1 if self.handlerdepth==1 and \ gtk.events_pending(): gtk.mainiteration() self.handlerdepth-=1 return
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
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With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide