nested_timer_ex

function nested_timer_ex
%% NESTED_TIMER_EX  Example of using nested functions for a timer callback
% NESTED_TIMER_EX embeds a stock ticker in your MATLAB Desktop
%
% This application uses a WSDL web service to provide live (albeit 20
% minute delayed) stock quotes.  By using a MATLAB timer object, it runs
% continuously as a background task (without blocking the MATLAB command
% line).
%
% This application is not meant to be a serious stock ticker - it is
% intended to highlight usage of nested functions.  If you really need to
% get live stock prices into MATLAB, please use the Datafeed Toolbox.
%
% 1/6/2010: The web service used by this example is no longer available.

% Scott Hirsch
% [e-mail]
% Copyright 2005-2010 The MathWorks, Inc

%% User Configurable Parameters
UpdateRate = 5;                 % How often to get new values (s)
NValuesMax = 20;               % Display axes width (in values, not seconds)
DefaultStockSymbol = 'GOOG';    % Default Stock ticker symbol


%% Create timer object
% We use a timer object to have MATLAB fetch the latest stock price at a
% fixed interval.  The callback function is a nested function, myCallback
t = timer;
t.ExecutionMode = 'fixedRate';
t.Period = UpdateRate;
t.TimerFcn = @myCallback;       % Handle to nested callback function below

%% Initialize graphics
% Build a lightweight user interface

% Create a docked figure.  Use a custom CloseRequestFcn to stop and delete
% the timer before closing.
hFig = figure('WindowStyle','docked','CloseRequestFcn',@closeFunction);

% Add text and and edit box for specifying the ticker symbol
hTickerText = uicontrol(hFig,'style','text','pos',[20 20 50 20],'string','Symbol:');
hTickerEdit = uicontrol(hFig,'style','edit','pos',[70 20 50 20 ], ...
    'string',DefaultStockSymbol,'BackgroundColor','white', ...
    'Callback',@myCallback);
% Note that updating the ticker symbol has the same behavior as the timer.

% Draw a blank line.  We'll replace it with live values as they come in.
time = (0:1:NValuesMax-1)*UpdateRate;
hLine = plot(time,NaN*ones(NValuesMax,1));
xlabel('s'); ylabel('$')

ind = 0;        % Initialize counter for plot update
drawnow         % Force a graphics draw before the timer starts

%% Start timer
start(t)        % This will call myCallback every UpdateRate seconds

    function myCallback(varargin)
        %myCallback  Callback function for stock ticker timer object
        %Don't bother specifying input arguments explicitly, since we don't
        %need them (but they are required by timer object).

        % Get quotes
        StockSymbol = get(hTickerEdit,'String');    % Current ticker symbol
        try
            price = localGetQuote(StockSymbol);     % Use WSDL service to get stock quote
        catch
            error(['Could not retrieve price for ' StockSymbol])
        end


        % Update display.  Replace values of hLine with latest stock prices
        ind = rem(ind+1,NValuesMax);if ind==0, ind=NValuesMax; end; % Increment index
        yd = get(hLine,'YData');
        yd(ind) = price;
        set(hLine,'YData',yd)
        title(['Stock Price: ' StockSymbol])

    end     % function myCallback

    function closeFunction(varargin)
        % closeFunction    CloseRequestFcn for stock ticker figure.

        % Stop and delete timer
        stop(t)
        delete(t)

        % Delete the figure
        delete(hFig)
    end

end     % function nested_timer_ex



function value = localGetQuote(symbol)
% LOCALGETQUOTE  Get stock quote
% LOCALGETQUOTE(SYMBOL) Gets a 20 minute delayed stock quote for SYMBOL

% localGetQuote is provided as a local function instead of a nested
% function because it doesn't really need general access to data in the
% main function.  It works well as a traditional function, with clearly
% defined input and output.

% Create the WSDL file if necessary
wsdlFile = 'DelayedQuotesService.wsdl';
wsdlUrl = 'http://services.xmethods.net/soap/urn:xmethods-delayed-quotes.wsdl';
if ~(exist(wsdlFile,'file') == 2)
    try
        urlwrite(wsdlUrl,wsdlFile);
    catch
        error('Unable to create WSDL file for DelayedQuotesService.wsdl');
    end
end

% Create class from WSDL file if necessary
if ~(exist('@StockQuoteService','dir') == 7)
    try
        % Create class from WSDL
        createClassFromWsdl(wsdlFile);
    catch
        % Throw error
        error('Unable to create WSDL class for StockQuoteService');
    end
end


sqs = StockQuoteService;            % Create StockQuoteService object
value = getQuote(sqs,symbol);       % Get current stock value
end % function localGetQuote