Since the data is very less. Read the file once during start-up of app and prepare the in-memory QMap. This QMap is used for any set/get calls by the app, don't read/write to file. Finally when we exit the app, write the QMap to file wiping out old contents.
On 27 June 2013 12:26, Mandeep Sandhu <mandeepsandhu....@gmail.com> wrote: > Hi, > > I wanted to know if I'm doing file i/o the right way in one of my apps. > > I'm writing a small helper class for one of my applications which is > supposed to store data, in the form of key-value pairs, in a file. This is > very similar to QSettings but w/o any fancy groups/sections that it > provides. So lets assume that I have to use a file based approach only! :) > > It provides 2 functions - get(key) and a set(key, value) and they behave > exactly like QMaps equivalent functions, i.e if the key exists, it'll > overwrite the value, else it'll add a new entry. This class takes either a > filename as input or a QFile itself. > > Assumptions:There won't be much data written to the file (max 1-2 KB). The > set function will not be called very often (probably once or twice in the > lifetime of the app). The get fxn will be called a little more often. > > Here's what I do in the 2 functions (skipping error condition checks keep > it simple): > > get(key): > * Open the file in Read-Only mode. > * Parse the data and prepare a QMap of the key-value pairs. > * Close the file > * Return the value for the key > > set(key, value): > * Open the file in Read-Only mode. > * Parse the data and prepare a QMap of the key-value pairs. > * Close the file > * Open the file in Write-Only & Truncate mode > * Insert the new key-value in the map > * Write the map > * Close the file > > In the set function I'm opening the file twice - once to read it's content > and prepare the map and next I open it in truncate mode as I want to wipe > off the existing data and write the new data afresh. > > Is there a simpler way to achieve what I'm doing with a file? I'm assuming > the 2 open-close calls in set() are ok as it won't be called very often. > > Thoughts? > > Thanks, > -mandeep > > > _______________________________________________ > Interest mailing list > Interest@qt-project.org > http://lists.qt-project.org/mailman/listinfo/interest > >
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