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The Slice compiler generates the following definition for use by the client:

classdef SimplePrx < Ice.ObjectPrx
    methods
        function op(obj, varargin)
            ...
        end
    end
    methods(Static)
        function id = ice_staticId()
            ...
        end
        function r = checkedCast(proxy, varargin)
            ...
        end
        function r = uncheckedCast(proxy, varargin)
            ...
        end
    end
    ...
end

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All Ice objects have Object as the ultimate ancestor type, so all proxies inherit from ObjectPrx. ObjectPrx provides a number of methods:

classdef ObjectPrx < handle
    methods
        function r = eq(obj, other)
        function r = ice_getIdentity(obj)
        function r = ice_isA(obj, id, varargin)
        function r = ice_ids(obj, varargin)
        function r = ice_id(obj, varargin)
        function ice_ping(obj, varargin)
        % ...
    end
end

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• ice_getIdentity
  This method returns the identity of the object denoted by the proxy. The identity of an Ice object has the following Slice type:

  Code Block
  language slice title Slice
  module Ice {     struct Identity {         string name;         string category;     } }

  To see whether two proxies denote the same object, first obtain the identity for each object and then compare the identities:

  Code Block
  language matlab title MATLAB
  proxy1 = ...; proxy2 = ...; id1 = proxy1.ice_getIdentity(); id2 = proxy2.ice_getIdentity(); if isequal(id1, id2)     % proxy1 and proxy2 denote the same object else     % proxy1 and proxy2 denote different objects end

• ice_isA
  The ice_isA method determines whether the object denoted by the proxy supports a specific interface. The argument to ice_isA is a type ID. For example, to see whether a proxy of type ObjectPrx denotes a Printer object, we can write:

  Code Block
  language matlab title MATLAB
  proxy = ...; if ~isempty(proxy) && proxy.ice_isA("::Printer")     % o denotes a Printer object else     % o denotes some other type of object end

  Note that we are testing whether the proxy is null before attempting to invoke the ice_isA method. This avoids getting an error if the proxy is an empty array.

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As we saw earlier, the Slice-to-MATLAB compiler generates static helper methods that support down-casting and type discovery:

classdef SimplePrx < Ice.ObjectPrx
    ...
    methods(Static)
        function id = ice_staticId()
            ...
        end
        function r = checkedCast(proxy, varargin)
            ...
        end
        function r = uncheckedCast(proxy, varargin)
            ...
        end
    end
    ...
end

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Given a proxy of any type, you can use a checkedCast to determine whether the corresponding object supports a given type, for example:

proxy = ...;        % Get a proxy from somewhere...

simple = SimplePrx.checkedCast(proxy);
if ~isempty(simple)
    % Object supports the Simple interface...
else
    % Object is not of type Simple...
end

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Suppose you expect to receive a proxy for a Process object and use an uncheckedCast to down-cast the proxy:

proxy = ...;                                % Get proxy...
process = ProcessPrx.uncheckedCast(proxy);  % No worries...
process.launch(40, 60);                     % Oops...

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The base proxy class ObjectPrx supports a variety of methods for customizing a proxy. Since proxies are immutable, each of these "factory methods" returns a copy of the original proxy that contains the desired modification. For example, you can obtain a proxy configured with a ten second invocation timeout as shown below:

proxy = communicator.stringToProxy(...);
proxy = proxy.ice_invocationTimeout(10000);

A factory method returns a new proxy object if the requested modification differs from the current proxy, otherwise it returns the current proxy. With few exceptions, factory methods return a proxy of the same type as the current proxy, therefore it is generally not necessary to repeat a checkedCast or uncheckedCast after using a factory method. Furthermore, the mapping generates type-specific factory methods so that no casts are necessary:

base = communicator.stringToProxy(...);
hello = HelloPrx.checkedCast(base);
hello = hello.ice_invocationTimeout(10000); % No cast is necessary
hello.sayHello();

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Proxies can be compared for equality using the == operator. Note that proxy comparison with == uses all of the information in a proxy for the comparison. This means that not only the object identity must match for a comparison to succeed, but other details inside the proxy, such as the protocol and endpoint information, must be the same. In other words, comparison with == tests for proxy identity, not object identity. A common mistake is to write code along the following lines:

proxy1 = ...;        % Get a proxy...
proxy2 = ...;        % Get another proxy...

if proxy1 == proxy2
    % proxy1 and proxy2 denote the same object         % Correct
else
    % proxy1 and proxy2 denote different objects       % WRONG!
end

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To compare the object identities of two proxies, you can use helper functions in the Ice package:

function r = proxyIdentityCompare(lhs, rhs)
function r = proxyIdentityAndFacetCompare(lhs, rhs)

proxyIdentityCompare allows you to correctly compare proxies for identity:

proxy1 = ...;        % Get a proxy...
proxy2 = ...;        % Get another proxy...

if Ice.proxyIdentityCompare(p1, p2) == 0
    % proxy1 and proxy2 denote the same object         % Correct
else
    % proxy1 and proxy2 denote different objects       % Correct
end

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